Project description:lean control, obese (DIO), aged 6 (young) or 18months (Aged) C57BL6N mice which underwent weight loss via intermittent calory restriction (ICR) or not (ad lib) were injected with E0771 cells and tumor growth was monitored
Project description:Younger age and obesity increase the incidence and rates of metastasis of triple-negative breast cancer (TNBC), an aggressive subtype of breast cancer. The tissue microenvironment, specifically the extracellular matrix (ECM), is known to promote tumor invasion and metastasis. We sought to characterize the effect of both age and obesity on the ECM of mammary fat pads. We used a diet-induced obesity (DIO) model where 10-week-old female mice were fed a high-fat diet (HFD) for 16 weeks or a control chow diet (CD) where time points were every 4 weeks to monitor age and obesity HFD progression. We isolated the mammary fat pads to characterize the ECM at each time point. Utilizing proteomics, we found that the early stages of obesity were sufficient to induce distinct differences in the ECM composition of mammary fat pads that promote TNBC cell invasion. ECM proteins previously implicated in driving TNBC invasion Collagen IV and Collagen VI, were enriched with weight gain. Together these data implicate ECM changes in the primary tumor microenvironment as mechanisms by which age and obesity contribute to breast cancer progression.
Project description:Background Understanding how obesity impacts human mammary adipose tissue (MAT) biology is crucial for deciphering its role in mammary epithelium during both physiological and pathophysiological processes, including breast cancer. Hypertrophic mammary adipocytes and Crown-like Structures are present in MAT of obese patients but whether these changes initiate a fibro-inflammatory response at the tissue level remains insufficiently explored. Objective We aimed to investigate the markers of adipose tissue dysfunction (immune cell infiltration, secretion pattern and fibrosis) in tumor-free MAT of obese versus lean patients Methods Tumor-free MAT were obtained from 61 lean and obese women who underwent mastectomy for breast cancer risk reduction or treatment. Immune and non-immune cell infiltration was determined using flow cytometry. Bulk transcriptomic was used to characterize the phenotype of CD206+ macrophages whose infiltration is increased in obese. Conditioned-medium were prepared from MAT to characterize their secretome and dose adipokines and cytokines by ELISA assay. The extra-cellular matrix (ECM) deposition was evaluated by Masson trichrome staining on cross-stained sections and 3D imaging of red picrosirius-stained tissues. Results We observed an increase in CD206+/HLA-DR+ macrophages in the stromal vascular fraction of MAT from obese patients compared to lean ones. Other immune cell infiltration and endothelial or adipose progenitor cell numbers were similar between groups. Bulk transcriptomics on CD206+ macrophages revealed a significant decrease in ECM component secretion and processing in obese samples. Additionally, no heightened secretion of pro-inflammatory cytokines or MCP-1 was noted in obese samples. ECM characterization indicated an absence of fibrosis, with obese MAT showing reduced collagen secretion and deposition compared to lean counterparts. Conclusions Obesity does not associate with inflammation or fibrosis in MAT, underscoring its unique behavior.
Project description:It is unclear whether liver dysfunction is implicated in obesity-related detrimental changes in brain structure and function. This study examineed associations between liver dysfunction and brain health in middle-aged participants with obesity and early-stage metabolic dysfunction-associated steatotic liver disease (MASLD). Using brain magnetic resonance imaging, neuropsychological tests, histological and biochemical characterization of liver biopsies, we showed that specific hallmarks of liver dysfunction (e.g. free cholesterol accumulation, early fibrosis) are associated with increased white matter hyperintensities and larger variations in cerebral blood flow indicating poorer cerebrovascular function. These associations were independent of age, sex, body mass index, diabetes and hypertension and corroborated by independent liver RNA-seq and pathway analysis highlighting the role of liver inflammation and cellular stress. Further associations with circulating IL-6 suggest systemic low-grade inflammation as potential mediator between liver and brain. Hence, in obesity at midlife, cerebrovascular health is independently associated with the pathological state of the liver.
Project description:From a forward mutagenetic screen to discover mutations associated with obesity, we identified mutations in the spag7 gene linked to metabolic dysfunction in mice. Here we show that SPAG7 KO mice are born smaller and develop obesity and glucose intolerance in adulthood. This obesity does not stem from hyperphagia, but a decrease in energy expenditure. The KO animals also display reduced exercise tolerance and muscle function due to impaired mitochondrial function. Furthermore, SPAG7-deficiency in developing embryos leads to intrauterine growth restriction, brought on by placental insufficiency, likely due to abnormal development of the placental junctional zone. This insufficiency leads to loss of SPAG7-deficient fetuses in utero and reduced birth weights of those that survive. We hypothesize that a “thrifty phenotype” is ingrained in SPAG7 KO animals during development that leads to adult obesity. Collectively, these results indicate that SPAG7 is essential for embryonic development and energy homeostasis later in life.
Project description:In this study, we conducted single-cell RNA sequencing (scRNA-seq) studies to investigate the impact of high-fat diet (HFD)-induced obesity on transcriptomic landscapes of stromal and immune cells in mammary glands of Brca1-/-;p53+/- mice, an animal breast cancer model. The scRNA-seq profiling data showed that five different subtypes of stromal fibroblasts existed in mouse mammary glands. HFD-induced obesity led to upregulated expression of extracellular matrix (ECM) genes (Col3a1, Col6a3, Eln, and Sparc) and downregulated expression of immunoregulatory genes (Iigp1, Ccl2, and Cxcl10) in these stromal subtype cells. These findings, taken together, suggest that obesity alters the ECM composition and immune ecosystem through modulating the functionality of mammary stromal cells. Moreover, scRNA-seq analysis of mammary immune cells indicated that HFD-induced obesity promoted the generation and/or recruiting of pro-tumorigenic M2 macrophages in mammary glands.
Project description:Background: The obesity epidemic and the aging population of many western countries together with their associated diseases are major challenges for the healthcare. As obesity is a risk factor for many age related diseases, such as cancer, it is of importance to understand their interaction and the underlying molecular mechanisms. Lately, epigenetic programming in the form of DNA methylation and have been recognized for its importance in aging, obesity and several diseases. Method: Herein, the methylation level was determined for around 27000 CpG-islands in 46 DNA samples from adult peripheral blood with microarrays. The dependence for each CpG island with age, obesity and their interaction was ascertained with a general linear model. Results: The methylation level of more than 100 genomic sites were significantly altered with increasing age together with 10 additional sites that were differentially methylated with age in obese and lean individuals. The majority of the genomic sites were hypermethylated during aging, including the telomerase catalytic subunit (TERT). However, age dependent hypermethylation was prohibited or reverted in 8 of 10 regions in obese where an interaction between age and obesity was observed. Moreover, one region (LINC00304) was differentially methylated in obese and lean. Conclusion: This study provides evidence for an obesity influence on age driven epigenetic changes, which provide a molecular link between aging and obesity. This link and the identified markers may prove to be valuable biomarkers for the understanding of the molecular basis of aging, obesity and associated diseases. Bisulphite converted DNA from the 24 obese and 22 lean women were hybridised to the Illumina Infinium 27k Human Methylation Beadchip v1.2
Project description:Background: The obesity epidemic and the aging population of many western countries together with their associated diseases are major challenges for the healthcare. As obesity is a risk factor for many age related diseases, such as cancer, it is of importance to understand their interaction and the underlying molecular mechanisms. Lately, epigenetic programming in the form of DNA methylation and have been recognized for its importance in aging, obesity and several diseases. Method: Herein, the methylation level was determined for around 27000 CpG-islands in 46 DNA samples from adult peripheral blood with microarrays. The dependence for each CpG island with age, obesity and their interaction was ascertained with a general linear model. Results: The methylation level of more than 100 genomic sites were significantly altered with increasing age together with 10 additional sites that were differentially methylated with age in obese and lean individuals. The majority of the genomic sites were hypermethylated during aging, including the telomerase catalytic subunit (TERT). However, age dependent hypermethylation was prohibited or reverted in 8 of 10 regions in obese where an interaction between age and obesity was observed. Moreover, one region (LINC00304) was differentially methylated in obese and lean. Conclusion: This study provides evidence for an obesity influence on age driven epigenetic changes, which provide a molecular link between aging and obesity. This link and the identified markers may prove to be valuable biomarkers for the understanding of the molecular basis of aging, obesity and associated diseases.