Adipose Tissue as an Endocrine Organ: An Update on Pro-inflammatory and Anti-inflammatory Microenvironment

Impact of acute psychological stress on cardiovascular risk factors in face of insulin resistance

Individuals with insulin resistance (IR) are at greater risk for cardiovascular disease (CVD). Psychological stress may contribute to develop CVD in IR, although mechanisms are poorly understood. Our aim was to test the hypothesis that individuals with IR have enhanced emotional and physiological responses to acute psychological stress, leading to increased CVD risk. Sixty participants were enrolled into the study, and classified into IR group (n = 31) and insulin sensitive group (n = 29) according to the Quantitative insulin sensitivity check index, which was calculated based on an oral glucose tolerance test. The Trier social stress test, a standardized experimental stress paradigm, was performed on each participant, and emotional and physiological responses were examined. Blood was collected from each subject for insulin, cytokines, and cortisol measurements. Compared with the insulin-sensitive group, individuals with IR had significantly lower ratings of energy and calm, but higher fatigue levels in response to acute stressors. Individuals with IR also showed blunted heart rate reactivity following stress. In addition, the IR status was worsened by acute psychological stress as demonstrated by further increased insulin secretion. Furthermore, individuals with IR showed significantly increased levels of leptin and interleukin-6, but decreased levels of adiponectin, at baseline, stress test, and post-stress period. Our findings in individuals with IR under acute stress would allow a better understanding of the risks for developing CVD and to tailor the interventions for better outcomes.

The association of visceral adipose tissue and subcutaneous adipose tissue with metabolic risk factors in a large population of Chinese adults

OBJECTIVE

Abdominal visceral (VAT) and subcutaneous (SAT) adipose tissues contribute to obesity, but may have different cardiometabolic risk profiles. We examined and compared the associations of abdominal VAT and SAT with metabolic risk factors in a large cohort of Chinese adults.

METHODS

This study was based on cross-sectional analysis of data from 1449 adults aged 40-65 years. VAT and SAT were assessed at L4-L5 level by magnetic resonance imaging. The associations of VAT and SAT with blood pressure, glucose and lipid were examined by linear regression stratified by sex and glucose tolerance status (normal glucose tolerance and prediabetes). Logistic regression was used to analyse the association of VAT and SAT with risk of hypertension, prediabetes and dyslipidaemia.

RESULTS

VAT was more strongly associated with metabolic risk factors. Higher VAT was associated with higher blood pressure (βmen = 3·99, P = 0·0002; βwomen = 6·46, P = 0·0002), higher triglyceride (βmen = 0·45, P < 0·0001; βwomen = 0·6, P < 0·0001), higher total cholesterol (βmen = 0·15, P = 0·02; βwomen = 0·37, P = 0·0002) and higher 2-h glucose levels (βmen = 0·68, P = 0·003; βwomen = 0·94, P < 0·0001). The association remained significant after subjects were stratified by glucose tolerance status. However, SAT was not associated with any additional risk factors. VAT was associated with increased risk of hypertension (OR = 1·97, P < 0·0001), prediabetes (OR = 1·53, P = 0·0007) and dyslipidaemia (OR = 2·40, P < 0·0001). These associations were not observed for SAT.

CONCLUSIONS

VAT was more strongly associated with cardiometabolic risk factors than SAT in a large cohort of Chinese adults. Higher VAT was associated with increased risk of hypertension, dyslipidaemia and prediabetes.

Does body mass index (BMI) influence the Ankylosing Spondylitis Disease Activity Score in axial spondyloarthritis?: Data from the SPACE cohort

Objective

Obesity is associated with elevated C reactive protein (CRP) levels. The Ankylosing Spondylitis Disease Activity Score (ASDAS) combines patient-reported outcomes (PROs) and CRP. We evaluated the effect of body mass index (BMI) on CRP and on ASDAS, and studied if ASDAS can be used in obese axial spondyloarthritis (axSpA) patients to assess disease activity.

Methods

Baseline data of patients with chronic back pain of short duration included in the SPondyloArthritis Caught Early (SPACE) cohort were used. Collected data included BMI and ASDAS. Patients were classified according to the ASAS axSpA classification criteria and BMI (overweight ≥25 and obese ≥30). Correlation and linear regression analyses were performed to assess the relation between BMI and ASDAS. Linear regression models were performed to assess if age or gender were effect modifiers in the relation between BMI and CRP, and between BMI and ASDAS.

Results

In total, 428 patients were analysed (n=168 axSpA; n=260 no-axSpA). The mean age was 31.1 years, 36.9% were male, 26.4% were overweight and 13.3% obese, median CRP was 3 mg/L and the mean ASDAS was 2.6. Gender was the only factor modifying the relationship between BMI and CRP as BMI had an influence on CRP only in females (β=0.35; p<0.001). Correlations between BMI and CRP or PROs were generally weak, and only significant for CRP in female patients. BMI was not related to ASDAS in axSpA patients.

Conclusions

ASDAS is not affected by BMI in axSpA patients. Therefore, based on our data it is not necessary to take BMI in consideration when assessing disease activity using ASDAS in axSpA patients.

Stress-induced alterations in estradiol sensitivity increase risk for obesity in women

The prevalence of obesity in the United States continues to rise, increasing individual vulnerability to an array of adverse health outcomes. One factor that has been implicated causally in the increased accumulation of fat and excess food intake is the activity of the limbic-hypothalamic-pituitary-adrenal (LHPA) axis in the face of relentless stressor exposure. However, translational and clinical research continues to understudy the effects sex and gonadal hormones and LHPA axis dysfunction in the etiology of obesity even though women continue to be at greater risk than men for stress-induced disorders, including depression, emotional feeding and obesity. The current review will emphasize the need for sex-specific evaluation of the relationship between stress exposure and LHPA axis activity on individual risk for obesity by summarizing data generated by animal models currently being leveraged to determine the etiology of stress-induced alterations in feeding behavior and metabolism. There exists a clear lack of translational models that have been used to study female-specific risk. One translational model of psychosocial stress exposure that has proven fruitful in elucidating potential mechanisms by which females are at increased risk for stress-induced adverse health outcomes is that of social subordination in socially housed female macaque monkeys. Data from subordinate female monkeys suggest that increased risk for emotional eating and the development of obesity in females may be due to LHPA axis-induced changes in the behavioral and physiological sensitivity of estradiol. The lack in understanding of the mechanisms underlying these alterations necessitate the need to account for the effects of sex and gonadal hormones in the rationale, design, implementation, analysis and interpretation of results in our studies of stress axis function in obesity. Doing so may lead to the identification of novel therapeutic targets with which to combat stress-induced obesity exclusively in females.

Spaceflight-induced vertebral bone loss in ovariectomized rats is associated with increased bone marrow adiposity and no change in bone formation

There is often a reciprocal relationship between bone marrow adipocytes and osteoblasts, suggesting that marrow adipose tissue (MAT) antagonizes osteoblast differentiation. MAT is increased in rodents during spaceflight but a causal relationship between MAT and bone loss remains unclear. In the present study, we evaluated the effects of a 14-day spaceflight on bone mass, bone resorption, bone formation, and MAT in lumbar vertebrae of ovariectomized (OVX) rats. Twelve-week-old OVX Fischer 344 rats were randomly assigned to a ground control or flight group. Following flight, histological sections of the second lumbar vertebrae (n=11/group) were stained using a technique that allowed simultaneous quantification of cells and preflight fluorochrome label. Compared with ground controls, rats flown in space had 32% lower cancellous bone area and 306% higher MAT. The increased adiposity was due to an increase in adipocyte number (224%) and size (26%). Mineral apposition rate and osteoblast turnover were unchanged during spaceflight. In contrast, resorption of a preflight fluorochrome and osteoclast-lined bone perimeter were increased (16% and 229%, respectively). The present findings indicate that cancellous bone loss in rat lumbar vertebrae during spaceflight is accompanied by increased bone resorption and MAT but no change in bone formation. These findings do not support the hypothesis that increased MAT during spaceflight reduces osteoblast activity or lifespan. However, in the context of ovarian hormone deficiency, bone formation during spaceflight was insufficient to balance increased resorption, indicating defective coupling. The results are therefore consistent with the hypothesis that during spaceflight mesenchymal stem cells are diverted to adipocytes at the expense of forming osteoblasts.

CpG Oligodeoxynucleotides Downregulate Placental Adiponectin and Increase Embryo Loss in Non-Obese Diabetic Mice

PROBLEM

CpG oligodeoxynucleotides (ODNs) can induce immunological changes in non-obese diabetic (NOD) mice and increase embryo loss, but little is known about the mechanism. This study aimed to determine the role of adiponectin in CpG ODN-induced pregnancy failure.

METHOD OF STUDY

Oligodeoxynucleotide 1826 was intraperitoneally injected to NOD mice, and ODN 2216, ODN 2006, and ODN 2395 were used to stimulate human trophoblast cell lines to investigate adiponectin expression patterns and its possible effects on trophoblast function.

RESULTS

CpG ODNs downregulated adiponectin via the cJun N-terminal kinase signaling pathway and led to increased embryo loss (from 6.9 to 33.3%). ODN 2006 impaired human trophoblast cell migration, which was successfully rescued by adiponectin treatment.

CONCLUSION

CpG ODNs decreased placental adiponectin expression in NOD mice and impaired human trophoblast function and was associated with increased embryo loss. Adiponectin may therefore play an important protective role in the prevention of bacteria-induced pregnancy failure.

[Obesity in metabolic syndrome, as well as kidney dysfunction]

The presence of metabolic syndrome (MS) in a patient allows him to be assigned to a group at high risk for atherosclerosis, cardiovascular events, coronary heart disease, and type 2 diabetes mellitus. In addition, MS negatively affects not only the heart and vessels, but also kidney function, which leads to chronic kidney disease (CKD). MS is pathogenetically associated with CKD and is an independent prognostic factor of the development of the latter, namely, the involvement of the kidney frequently determines prognosis and quality of life in these patients. The paper gives a modern view on the concept of MS and CKD and considers its main diagnostic criteria, etiology, and pathogenesis. The study of the relationships between MS and CKD may suggest that the high prevalence of kidney dysfunction in the general population is largely determined by metabolic nephropathies, including obesity-related nephropathy. The identification of risk factors and poor prognostic markers in this category of patients seems to be extremely important for the early diagnosis of the disease and their timely elimination is one of the main approaches to the comprehensive prevention of CKD in these patients.