Vincent Achard

Adipose tissue transcriptomic signature highlights the pathological relevance of extracellular matrix in human obesity

BackgroundInvestigations performed in mice and humans have acknowledged obesity as a low-grade inflammatory disease. Several molecular mechanisms have been convincingly shown to be involved in activating inflammatory processes and altering cell composition in white adipose tissue (WAT). However, the overall importance of these alterations, and their long-term impact on the metabolic functions of the WAT and on its morphology, remain unclear.ResultsHere, we analyzed the transcriptomic signature of the subcutaneous WAT in obese human subjects, in stable weight conditions and after weight loss following bariatric surgery. An original integrative functional genomics approach was applied to quantify relations between relevant structural and functional themes annotating differentially expressed genes in order to construct a comprehensive map of transcriptional interactions defining the obese WAT. These analyses highlighted a significant up-regulation of genes and biological themes related to extracellular matrix (ECM) constituents, including members of the integrin family, and suggested that these elements could play a major mediating role in a chain of interactions that connect local inflammatory phenomena to the alteration of WAT metabolic functions in obese subjects. Tissue and cellular investigations, driven by the analysis of transcriptional interactions, revealed an increased amount of interstitial fibrosis in obese WAT, associated with an infiltration of different types of inflammatory cells, and suggest that phenotypic alterations of human pre-adipocytes, induced by a pro-inflammatory environment, may lead to an excessive synthesis of ECM components.ConclusionThis study opens new perspectives in understanding the biology of human WAT and its pathologic changes indicative of tissue deterioration associated with the development of obesity.

Postnatal Programming of Glucocorticoid Metabolism in Rats Modulates High-Fat Diet–Induced Regulation of Visceral Adipose Tissue Glucocorticoid Exposure and Sensitivity and Adiponectin and Proinflammatory Adipokines Gene Expression in Adulthood

OBJECTIVE—Alterations of the perinatal environment, which lead to increased prevalence of the metabolic syndrome in adulthood, program an upregulation of systemic and/or adipose tissue glucocorticoid metabolism (11β-hydroxysteroid dehydrogenase type 1 [11β-HSD-1]-induced corticosterone reactivation). We hypothesized that postnatal programming could modulate high-fat diet–induced adipose tissue dysregulation in adulthood. RESEARCH DESIGN AND METHODS—We compared the effects of chronic (since weaning) high- or low-fat diet in postnatally normofed (control) or overfed (programmed) rats. RESULTS—Postnatal programming accentuated high-fat diet–induced overweight, insulin resistance, glucose intolerance, and decrease in circulating and epididymal adipose tissue adiponectin. Neither manipulation altered liver function. Postnatal programming or high-fat diet increased systemic corticosterone production, which was not further modified when both manipulations were associated. Postnatal programming suppressed high-fat diet–induced decrease in mesenteric adipose tissue (MAT) glucocorticoid sensitivity and triggered high-fat diet–induced increase in MAT glucocorticoid exposure, subsequent to enhanced MAT 11β-HSD-1 gene expression. MAT tumor necrosis factor (TNF)-α, TNF-receptor 1, interleukin (IL)-6, resistin, and plasminogen activator inhibitor-1 mRNAs were not changed by high-fat feeding in control rats and showed a large increase in programmed animals, with this effect further enhanced by high-fat diet for TNF-α and IL-6. CONCLUSIONS—Our data show for the first time that postnatal manipulation programs high-fat diet–induced upregulation of MAT glucocorticoid exposure, sensitivity, and inflammatory status and therefore reveal the pivotal role of the environment during the perinatal period on the development of diet-induced adipose tissue dysregulation in adulthood. They also urge the need for clinical trials with specific 11β-HSD-1 inhibitors.

The Intensity of IUGR-Induced Transcriptome Deregulations Is Inversely Correlated with the Onset of Organ Function in a Rat Model

A low-protein diet applied during pregnancy in the rat results in intrauterine growth restricted (IUGR) fetuses. In humans, IUGR is associated with increased perinatal morbidity, higher incidence of neuro-developmental defects and increased risk of adult metabolic anomalies, such as diabetes and cardiovascular disease. Development and function of many organs are affected by environmental conditions such as those inducing fetal and early postnatal growth restriction. This phenomenon, termed “fetal programming” has been studied unconnectedly in some organs, but very few studies (if any) have investigated at the same time several organs, on a more comparative basis. However, it is quite probable that IUGR affects differentially most organ systems, with possible persistent changes in gene expression. In this study we address transcriptional alterations induced by IUGR in a multi-organ perspective, by systematic analysis of 20-days rat fetuses. We show that (1) expressional alterations are apparently stronger in organs functioning late in foetal or postnatal life than in organs that are functioning early (2) hierarchical classification of the deregulations put together kidney and placenta in one cluster, liver, lungs and heart in another; (3) the epigenetic machinery is set up especially in the placenta, while its alterations are rather mild in other organs; (4) the genes appear deregulated in chromosome clusters; (5) the altered expression cascades varies from organ to organ, with noticeably a very significant modification of the complement and coagulation cascades in the kidney; (6) we found a significant increase in TF binding site for HNF4 proteins specifically for liver genes that are down-regulated in IUGR, suggesting that this decrease is achieved through the action of HNF transcription factors, that are themselves transcriptionnally induced in the liver by IUGR (x 1.84 fold). Altogether, our study suggests that a combination of tissue-specific mechanisms contributes to bring about tissue-driven modifications of gene cascades. The question of these cascades being activated to adapt the organ to harsh environmental condition, or as an endpoint consequence is still raised.

Occupational Exposures Obtained by Questionnaire in Clinical Practice and Their Association With Semen Quality

In industrial countries, evidence suggests that semen quality has been steadily decreasing over the past 5 decades. We employed a short questionnaire to examine the association between self-reported physical or chemical occupational exposures and semen quality. The study included 402 men consulting for couple infertility (314 with oligospermia, asthenospermia, or teratospermia and 88 with normal semen; World Health Organization criteria). Exposure effects on global sperm quality and total sperm count, sperm motility, and sperm morphology were investigated. We found significant associations between semen impairment and occupational risk factors such as exposure to heavy metals (adjusted odds ratio [OR] = 5.4; 95% confidence interval [CI], 1.6-18.1), solvents (OR = 2.5; 95% CI, 1.4-4.4), fumes (OR = 1.9; 95% CI, 1.1-3.4), and polycyclic aromatic hydrocarbons (OR = 1.9; 95% CI, 1.1-3.5). Exposure to pesticides or cement was nearly significant (OR = 3.6; 95% CI, 0.8-15.8, and OR = 2.5; 95% CI, 0.95-6.5, respectively). Physical risk factors were associated with some sperm anomalies, such as mechanical vibrations with oligospermia and teratospermia as well as excess heat and extended sitting periods with impaired motility. Exposure to ionizing radiation and electromagnetic fields was not associated with semen impairment; these results, however, may be skewed, because very few subjects reported such exposure. Despite the small dataset, self-reported exposures were correlated with semen impairment. This approach may be recommended in routine clinical practice to seek relationships between occupational exposures to reprotoxic agents and impaired semen parameters. This knowledge would allow preventive measures in the workplace to be established and could be complemented by the use of biomarkers to better characterize exposure to chemical substances and their spermiotoxic effects.

Prognosis factors of pregnancy after intrauterine insemination with the husband's sperm: conclusions of an analysis of 2,019 cycles

OBJECTIVE To identify the prognostic factors for pregnancy after intrauterine insemination with the husbands sperm (IUI-H). DESIGN Retrospective study. SETTING A single university medical center. PATIENT(S) 851 couples, for 2,019 IUI-H cycles. INTERVENTION(S) After controlled ovarian stimulation, IUI-H performed 36 hours after ovulation triggering or 24 hours after a spontaneous luteinizing hormone (LH) surge. MAIN OUTCOME MEASURE(S) Clinical pregnancy rate per cycle (PR) and delivery rate per cycle (DR). RESULT(S) The overall PR was 14.8% and DR 10.8%. Higher PR and DR were observed for patients presenting with ovulation disorders (particularly polycystic ovary syndrome) or with male infertility. Secondary infertility in the woman appeared to be a positive prognostic factor as did a basal follicle-stimulating hormone (FSH) level ≤ 7 IU/L and ovulation triggering over spontaneous LH rise. The other parameters influencing the results were the womens age, the number of mature follicles obtained (≥ 2), the endometrial thickness (10-11 mm), and the number of progressive motile spermatozoa inseminated (>1 million). CONCLUSION(S) In women aged ≤ 38 years, IUI-H should be considered as an option, particularly in cases of female infertility from ovulation disorders, in cases of a normal ovarian reserve, in cases of secondary infertility, or when ≥ 1 million progressive sperm are inseminated. Bifollicular stimulation is required. In other cases, in vitro fertilization should be discussed as the first-line treatment.

Perinatal Programming of Central Obesity and the Metabolic Syndrome: Role of Glucocorticoids

Intrauterine growth retardation (IUGR) is associated with increased prevalence, at the adult age, of central obesity, the metabolic syndrome, and its complications (type 2 diabetes and coronary heart disease). Programming of the corticotropic function is one of the mechanisms underlying the above-mentioned phenomenon. An increased passage of active glucocorticoids from the mother to the fetus can act, at the central nervous system level, to program an enhanced response to stress and, at the peripheral level, in adipose tissue to induce an increased local glucocorticoid exposure and sensitivity. In addition to an improvement of the health of pregnant women, early diagnosis of metabolic and hormonal disturbances is important in children with IUGR, in order to prevent a compensatory catch-up growth and its subsequent obesity, and to set up a therapeutic intervention against the deleterious consequences of hypercorticism.

Cerium dioxide nanoparticles affect in vitro fertilization in mice

Abstract Due to their catalytic and oxidative properties, cerium dioxide nanoparticles (CeO2NPs) are widely used as diesel additive or as promising therapy in cancerology; yet, scarce data are available on their toxicity, and none on their reproductive toxicity. We showed a significant decrease of fertilization rate, assessed on 1272 oocytes, during in vitro fertilization (IVF) carried out in culture medium containing CeO2NP at very low concentration (0.01 mg.l−1). We also showed significant DNA damage induced in vitro by CeO2NP on mouse spermatozoa and oocytes at 0.01 mg.l−1 using Comet assay. Transmission Electron Microscopy did not detect any nanoparticles in the IVF samples at 0.01 mg.l−1, but showed, at high concentration (100 mg.l−1), their endocytosis by the cumulus cells surrounding oocytes and their accumulation along spermatozoa plasma membranes and oocytes zona pellucida. We did not observe any nanoparticles in the cytoplasm of spermatozoa, oocytes or embryos. This study demonstrates for the first time the impact of CeO2NP on in vitro fertilization, as well as their genotoxicity on mouse spermatozoa and oocytes, at low nanoparticle concentration exposure. Decreased fertilization rates may result from: (1) CeO2NP’s genotoxicity on gametes; (2) a mechanical effect, disrupting gamete interaction and (3) oxidative stress induced by CeO2NP. These results add new and important insights with regard to the reproductive toxicity of nanomaterials requesting urgent evaluation, and support several publications on metal nanoparticles reprotoxicity. Our data highlight the need for in vivo studies after low-dose exposure.

Persistence of Coxiella burnetii, the Agent of Q Fever, in Murine Adipose Tissue

Coxiella burnetii, the agent of Q fever, is known to persist in humans and rodents but its cellular reservoir in hosts remains undetermined. We hypothesized that adipose tissue serves as a C. burnetii reservoir during bacterial latency. BALB/c and C57BL/6 mice were infected with C. burnetii by the intraperitoneal route or the intracheal route. Adipose tissue was tested for the presence of C. burnetii several months after infection. C. burnetii was detected in abdominal, inguinal and dorsal adipose tissue 4 months post-infection, when no bacteria were detected in blood, liver, lungs and spleen, regardless of the inoculation route and independently of mouse strain. The transfer of abdominal adipose tissue from convalescent BALB/c mice to naïve immunodeficient mice resulted in the infection of the recipient animals. It is likely that C. burnetii infects adipocytes in vivo because bacteria were found in adipocytes within adipose tissue and replicated within in vitro-differentiated adipocytes. In addition, C. burnetii induced a specific transcriptional program in in-vivo and in vitro-differentiated adipocytes, which was enriched in categories associated with inflammatory response, hormone response and cytoskeleton. These changes may account for bacterial replication in in-vitro and chronic infection in-vivo. Adipose tissue may be the reservoir in which C. burnetii persists for prolonged periods after apparent clinical cure. The mouse model of C. burnetii infection may be used to understand the relapses of Q fever and provide new perspectives to the follow-up of patients.

Expression and nutritional regulation of the (pro)renin receptor in rat visceral adipose tissue

Background: Early life nutritional environment plays an important role in the development of visceral adipose tissue and interacts with nutritional regulations in adulthood, leading to metabolic dysregulations. Aim: We hypothesized that the renin-angiotensin system may play a role in the programming-induced development of visceral adipose tissue. Material and methods: We studied, using a model of programming of overweight and glucose intolerance, obtained by post-natal overfeeding with consecutive high-fat diet, the status of plasma renin activity and mesenteric adipose renin-angiotensin system, including the recently identified (pro)renin receptor, in adult rats. Results: Post-natal overfeeding or high-fat feeding lead to overweight with increased visceral fat mass and adipocytes surface. When both paradigms were associated, adipocytes surface showed a disproportionate increase. A strong immunoreactivity for (pro)renin receptor was found in stromal cells. Plasma renin activity increased in programmed animals whereas (pro)renin receptor expressing cells density was stimulated by high-fat diet. There was a positive, linear relationship between plasma renin activity and (pro)renin receptor expressing cells density and adipocytes surface. Conclusions: Our experiments demonstrate that association of post-natal overfeeding and high-fat diet increased plasma renin activity and adipose (pro)renin receptor expression. Such phenomenon could explain, at least in part, the associated disproportionate adipocyte hypertrophy and its accompanying increased glucose intolerance.

Nuclear envelope remodelling during human spermiogenesis involves somatic B-type lamins and a spermatid specific B3 lamin isoform

The nuclear lamina (NL) is a filamentous protein meshwork, composed essentially of lamins, situated between the inner nuclear membrane and the chromatin. There is mounting evidence that the NL plays a role in spermatid differentiation during spermiogenesis. The mouse spermatid NL is composed of the ubiquitous lamin B1 and the spermatid-specific lamin B3, an N-terminally truncated isoform of lamin B2. However, nothing is known about the NL in human spermatids. We therefore investigated the expression pattern and localization of A-type lamins (A, C and C2) and B-type lamins (B1, B2 and B3) during human spermiogenesis. Here, we show that a lamin B3 transcript is present in human spermatids and that B-type lamins are the only lamins detectable in human spermatids. We determine that, as shown for their mouse counterparts, human lamin B3, but not lamin B2, induces strong nuclear deformation, when ectopically expressed in HeLa cells. Co-immunofluorescence revealed that, in human spermatids, B-type lamins are present at the nuclear periphery, except in the region covered by the acrosome, and that as the spermatid matures the B-type lamins recede towards the posterior pole. Only lamin B1 remains detectable on 33-47% of ejaculated spermatozoa. On spermatozoa selected for normal head density, however, this fell to <6%, suggesting that loss of the NL signal may be linked to complete sperm nucleus compaction. The similarities revealed between lamin expression during human and rodent spermiogenesis, strengthen evidence that the NL and lamin B3 have conserved functions during the intense remodelling of the mammalian spermatid nucleus.