Glucocorticoid-induced Fingerprints on Visceral Adipose Tissue Transcriptome and Epigenome

CONTEXT

Chronic glucocorticoid (GC) overexposure, resulting from endogenous Cushing's syndrome (CS) or exogenous GC therapy, causes several adverse outcomes, including persistent central fat accumulation associated with a low-grade inflammation. However, no previous multiomics studies in visceral adipose tissue (VAT) from patients exposed to high levels of unsuppressed GC during active CS or after remission are available yet.

OBJECTIVE

To determine the persistent VAT transcriptomic alterations and epigenetic fingerprints induced by chronic hypercortisolism.

METHODS

We employed a translational approach combining high-throughput data on endogenous CS patients and a reversible CS mouse model. We performed RNA sequencing and chromatin immunoprecipitation sequencing on histone modifications (H3K4me3, H3K27ac, and H3K27me3) to identify persistent transcriptional and epigenetic signatures in VAT produced during active CS and maintained after remission.

RESULTS

VAT dysfunction was associated with low-grade proinflammatory status, macrophage infiltration, and extracellular matrix remodeling. Most notably, chronic hypercortisolism caused a persistent circadian rhythm disruption in VAT through core clock genes modulation. Importantly, changes in the levels of 2 histone modifications associated to gene transcriptional activation (H3K4me3 and H3K27ac) correlated with the observed differences in gene expression during active CS and after CS remission.

CONCLUSION

We identified for the first time the persistent transcriptional and epigenetic signatures induced by hypercortisolism in VAT, providing a novel integrated view of molecular components driving the long-term VAT impairment associated with CS.

Central obesity, smoking habit, and hypertension are associated with lower antibody titres in response to COVID-19 mRNA vaccine

AIMS

To explore variables associated with the serological response following COVID-19 mRNA vaccine.

METHODS

Eighty-six healthcare workers adhering to the vaccination campaign against COVID-19 were enrolled in January-February 2021. All subjects underwent two COVID-19 mRNA vaccine inoculations (Pfizer/BioNTech) separated by 3 weeks. Blood samples were collected before the 1st and 1-4 weeks after the second inoculation. Clinical history, demographics, and vaccine side effects were recorded. Baseline anthropometric parameters were measured, and body composition was performed through dual-energy-X-ray absorptiometry.

RESULTS

Higher waist circumference was associated with lower antibody (Ab) titres (R = -0.324, p = 0.004); smokers had lower levels compared to non-smokers [1099 (1350) vs. 1921 (1375), p = 0.007], as well as hypertensive versus normotensive [650 ± 1192 vs. 1911 (1364), p = 0.001] and dyslipideamic compared to those with normal serum lipids [534 (972) vs 1872 (1406), p = 0.005]. Multivariate analysis showed that higher waist circumference, smoking, hypertension, and longer time elapsed since second vaccine inoculation were associated with lower Ab titres, independent of BMI, age. and gender.

CONCLUSIONS

Central obesity, hypertension, and smoking are associated with lower Ab titres following COVID-19 vaccination. Although it is currently impossible to determine whether lower SARS-CoV-2 Abs lead to higher likelihood of developing COVID-19, it is well-established that neutralizing antibodies correlate with protection against several viruses including SARS-CoV-2. Our findings, therefore, call for a vigilant approach, as subjects with central obesity, hypertension, and smoking could benefit from earlier vaccine boosters or different vaccine schedules.

Role of Adipose Tissue in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs), chronic inflammatory disorders affecting the gastrointestinal tract, include Crohn's disease and ulcerative colitis. There are increasing clinical and experimental data showing that obesity, especially visceral adiposity, plays a substantial role in the pathogenesis of IBD. Obesity seems to be an important risk factor also for IBD disease severity and clinical outcomes. Visceral adipose tissue is an active multifunctional metabolic organ involved in lipid storage and immunological and endocrine activity. Bowel inflammation penetrates the surrounding adipose tissue along the mesentery. Mesenteric fat serves as a barrier to inflammation and controls immune responses to the translocation of gut bacteria. At the same time, mesenteric adipose tissue may be the principal source of cytokines and adipokines responsible for inflammatory processes associated with IBD. This review is particularly focusing on the potential role of adipokines in IBD pathogenesis and their possible use as promising therapeutic targets.

Higher levels of physical activity are associated with reduced tethering and migration of pro-inflammatory monocytes in males with central obesity

Despite evidence that monocyte migration is accentuated by central adiposity, the impact of physical activity (PA) and exercise, particularly in the post-prandial state, on limiting migration are not established. We hypothesised that PA and a single bout of walking exercise would be associated with reduced ex vivo monocyte tethering and migration in middleaged males with central obesity (CO). Objective levels of PA were measured for 7 days in lean males (LE, N=12, mean (SD) age 39 (10) years, waist circumference 81.0 (6.3) cm) and males with CO (N=12, mean (SD) age 40 (9) years, waist circumference 115.3 (13.9) cm), followed by donation of a fasted blood sample. On the same day, CO undertook a bout of walking exercise, before donation of a second fasted blood sample. An ex vivo assay, coupled to flow cytometry, determined tethering and migration of classical, intermediate, and non-classical monocytes. C-C and CXC chemokine receptor (CCR2, CCR5 and CX3CR1) expression were also determined on total and classical monocytes. Monocyte subsets (total, classical, intermediate and CCR2+ monocytes), metabolic (glucose and lipids) and inflammatory (C-reactive protein) markers were greater in CO vs. LE (lower highdensity lipoprotein); however, adjustments for PA mitigated group differences for glucose, lipids, and monocyte subsets. Ex vivo tethering and migration (absolute and relative) of most monocyte subsets was greater in CO vs LE. Relative monocyte tethering and migration was largely not influenced by PA; however, higher PA was associated with reduced absolute migration and tethering of CD16 expressing monocytes in CO. Prior walking had no impact on these variables. These results highlight that regular PA, not single exercise bouts may limit the migration of pro-inflammatory monocytes in CO. These changes may relate to physiological parameters in blood (i.e. number of cells and their adhesion), rather than differences in chemokine receptor expression.

Abdominal Obesity Phenotypes and Incidence of Thyroid Autoimmunity: A 9-Year Follow-up

PURPOSE

The association between obesity and autoimmune diseases has been suggested by several previous studies. The objective of our study was to assess the association of abdominal obesity phenotypes with thyroid autoimmunity.

MATERIALS AND METHODS

This study was conducted within the framework of a population-based cohort study, Tehran Thyroid Study (TTS) on 4708 subjects without thyroid autoimmunity at baseline. Participants were categorized into four abdominal obesity phenotypes according to waist circumference (WC) and other metabolic syndrome components. Serum concentrations of thyroid peroxidase antibody (TPOAb), free T4 (FT4), thyrotropin (TSH), glucose, and lipid profiles were measured after 3, 6 and 9 years of follow-up. Cox proportional hazard models were used to evaluate associations of different phenotypes with the incidence of thyroid autoimmunity, adjusted for age, sex, FT4, and TSH.

RESULTS

Highest and lowest incidence rates of TPOAb positivity were observed among metabolically unhealthy, non-abdominally obese (MUNAO) [8.78 (7.31-10.55) per 1000 person-years of follow-up] and metabolically unhealthy abdominally obese (MUAO) [4.98 (3.88-6.41) per 1000 person-years of follow-up] phenotypes. Considering the metabolically healthy non-abdominal obese (MHNAO) individuals as reference, none of metabolically healthy abdominally obese (MHAO), MUNAO, and MUAO phenotypes were associated with increased risk of developing TPOAb positivity. Compared to individuals with high WC, the incidence rate (95%CI) of TPOAb positivity was higher among those with normal WC: 8.44 (7.13-10.0) vs 5.11 (4.01-6.51) per 1000 person-years, respectively. Higher WC was not associated with incident TPOAb positivity.

CONCLUSION

There was no significant association between baseline abdominal obesity phenotype status and development of TPOAb positivity over 9 years of follow-up.

Impact of Obesity and Adiposity on Inflammatory Markers in Patients With Rheumatoid Arthritis

OBJECTIVE

The C-reactive protein (CRP) level and erythrocyte sedimentation rate (ESR) are important disease activity biomarkers in rheumatoid arthritis (RA). This study aimed to determine to what extent obesity biases these biomarkers.

METHODS

Body mass index (BMI) associations with CRP level and ESR were assessed in 2 RA cohorts: the cross-sectional Body Composition (BC) cohort (n = 451), including whole-body dual x-ray absorptiometry measures of fat mass index; and the longitudinal Veterans Affairs Rheumatoid Arthritis (VARA) registry (n = 1,652), using multivariable models stratified by sex. For comparison, associations were evaluated in the general population using the National Health and Nutrition Examination Survey.

RESULTS

Among women with RA and in the general population, greater BMI was associated with greater CRP levels, especially among women with severe obesity (P < 0.001 for BMI ≥35 kg/m2 versus 20-25 kg/m2 ). This association remained after adjustment for joint counts and patient global health scores (P < 0.001 in BC and P < 0.01 in VARA), but was attenuated after adjustment for fat mass index (P = 0.17). Positive associations between BMI and ESR in women were more modest. In men with RA, lower BMI was associated with higher CRP levels and ESR, contrasting with positive associations among men in the general population.

CONCLUSION

Obesity is associated with higher CRP levels and ESR in women with RA. This association is related to fat mass and not RA disease activity. Low BMI is associated with higher CRP levels in men with RA; this unexpected finding remains incompletely explained but likely is not a direct effect of adiposity.

Effects of Mixed Carotenoids on Adipokines and Abdominal Adiposity in Children: A Pilot Study

CONTEXT

Carotenoids have been implicated in the regulation of adipocyte metabolism.

OBJECTIVE

To compare the effects of mixed-carotenoid supplementation (MCS) versus placebo on adipokines and the accrual of abdominal adiposity in children with obesity.

DESIGN AND SETTING

Randomized (1:1), double-blind, placebo-controlled intervention trial to evaluate the effects of MCS over 6 months in a subspecialty clinic.

PARTICIPANTS

Twenty (6 male and 14 female) children with simple obesity [body mass index (BMI) > 90%], a mean age (± standard deviation) of 10.5 ± 0.4 years, and Tanner stage I to V were enrolled; 17 participants completed the trial.

INTERVENTION

MCS (which contains β-carotene, α-carotene, lutein, zeaxanthin, lycopene, astaxanthin, and γ-tocopherol) or placebo was administered daily.

MAIN OUTCOME MEASURES

Primary outcomes were change in β-carotene, abdominal fat accrual (according to magnetic resonance imaging), and BMI z-score; secondary outcomes were adipokines and markers of insulin resistance.

RESULTS

Cross-sectional analysis of β-carotene showed inverse correlation with BMI z-score, waist-to-height ratio, visceral adipose tissue, and subcutaneous adipose tissue (SAT) at baseline. MCS increased β-carotene, total adiponectin, and high-molecular-weight adiponectin compared with placebo. MCS led to a greater reduction in BMI z-score, waist-to-height ratio, and SAT compared with placebo. The percentage change in β-carotene directly correlated with the percentage change in SAT.

CONCLUSIONS

The decrease in BMI z-score, waist-to-height ratio, and SAT and the concomitant increase in the concentration of β-carotene and high-molecular-weight adiponectin by MCS suggest the putative beneficial role of MCS in children with obesity.

Association of endotoxaemia with serum free fatty acids in metabolically healthy and unhealthy abdominally obese individuals: a case-control study in northwest of Iran

OBJECTIVES

This study aimed to compare serum free fatty acids (FFAs) and lipopolysaccharide-binding protein (LBP) between metabolically healthy abdominally obese (MHAO) and metabolically unhealthy abdominally obese (MUAO) individuals. We also examined the association between serum FFAs and LBP in the participants.

METHODS

In this age-matched and gender-matched case-control study, 164 abdominally obese subjects were recruited from June to November 2015 in the northwest of Iran. Demographic data, dietary intake, body composition, anthropometric indices and physical activity (PA) were assessed. Basal blood samples were collected to determine serum metabolic parameters, FFAs and LBP. Abdominal obesity was defined as having waist circumference ≥95 cm. Those with three or more metabolic alterations were defined as MUAO and those having two or less were classified as MHAO. Data were analysed using SPSS V.17.0.

RESULTS

There were no significant differences in dietary intake, anthropometric indices, body composition and PA between the two groups. The odds of MUAO significantly increased by increments in serum fasting blood sugar (OR 3.79, 95% CI 2.25 to 6.40), triglycerides (OR 1.10, 95% CI 1.05 to 1.15), systolic blood pressure (OR 1.02, 95% CI 1.00 to 1.04) and diastolic blood pressure (OR 1.03, 95% CI 1.01 to 1.06) and decreased by increase in serum high-density lipoprotein cholesterol (OR 0.32, 95% CI 0.20 to 0.52). The levels of LBP and FFAs showed no significant differences between the two groups. However, significant correlations were found between LBP and FFAs in pooled population (r=0.712; p<0.001) as well as in cases (r=0.717; p<0.001) and controls (r=0.704; p<0.001). Neither FFAs nor LBP were significantly correlated with dietary intake or metabolic parameters (p>0.05).

CONCLUSION

The results indicated that serum LBP and FFAs are highly correlated both in MHAO and MUAO states. In addition, the levels of LBP and FFAs seem to be more related to abdominal obesity than to the presence or absence of metabolic health.

[THE MODE OF EVALUATION OF FUNCTIONAL ACTIVITY OF C3-CONVERTASE OF CLASSIC PATH OF ACTIVATION OF COMPLEMENT]

The technique of detection of stabilization of C3-convertase classical way of activation of system of complement inhuman blood serum. The technique comprises two stages and is based on applying a reaction of lysis of erythrocytes of sheep sensitized by antibodies using 0.8% human blood serum. Preliminary an incubation of two samples (experimental and control) is applied during 10 min. and then reaction of activation of complement is stopped by adding a buffer containing 10 mM of EDTA. In control sample degree of lysis of erythrocytes is established and experimental sample is additionally incubated during 30 min at 37oC and then degree of lysis is determined. The activity of C3-convertase is calculated as a difference between degree of lysis and in experimental and control samples. The difference more than 10% is considered as a pathological state conditioned by stabilization of C3-convertase of classical way of activation of system of complement. The studies were carried out concerning stabilization of C3-convertase of classical way of activation of compliment in 31 patients with abdominal obesity. It is demonstrated that in 87% of patients with abdominal obesity stabilization of C3-convertase was established.

Inflammation mediates the association between visceral adiposity and obstructive sleep apnea in adolescents

Only a handful of studies, primarily in clinical samples, have reported an association between obesity, inflammation, and obstructive sleep apnea (OSA) in children and adolescents. No studies, however, have examined the pathogenetic link between visceral adiposity, systemic inflammation, and incident OSA in a large general population sample using objective measures of sleep and body fat. Adolescents (n = 392; mean age 17.0 ± 2.2 yr, 54.0% male) from the Penn State Child Cohort (PSCC) underwent 9-h overnight polysomnography; a DXA scan to assess body fat distribution; and a single fasting blood draw for the assessment of plasma interleukin-6 (IL-6), IL-6 soluble receptor (IL-6 sR), tumor necrosis factor alpha (TNFα), tumor necrosis factor receptor 1A (TNFR1), C-reactive protein (CRP), leptin, and adiponectin levels via ELISA. Visceral fat area was significantly elevated in moderate OSA (AHI ≥ 5), especially in boys. IL-6, CRP, and leptin were highest in adolescents with moderate OSA, even after adjusting for BMI percentile. Mediation analysis revealed that 42% of the association between visceral fat and OSA in adolescents was mediated by IL-6 (p = 0.03), while 82% of the association was mediated by CRP (p = 0.01). These data are consistent with the model of a feed-forward, vicious cycle, in which the release of proinflammatory cytokines by visceral adipocytes largely explains the association between central obesity and OSA; in turn, inflammation is also elevated in OSA independent of BMI. These findings, in a large, representative, non-clinical sample of young people, add to our understanding of the developmental pathogenesis of sleep apnea.

Associations between excessive adiposity and seroprevalence of herpes simplex virus type 1 and type 2 among US adults: a population-based age-period-cohort analysis

OBJECTIVES

Evidence on the association between herpes simplex virus (HSV) and excessive adiposity, such as obesity (body mass index ≥30 kg/m2) and abdominal obesity (waist circumference (WC) >102 or 88 cm), has been inconsistent. We sought to examine whether age-period-cohort (APC) effects could explain for the observed heterogeneities.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Adults aged 20-49 years with available serological data in the National Health and Nutrition Examination Survey (NHANES) in 1999-2012.

EXPOSURE MEASURES

Obesity and abdominal obesity.

RESULTS

In men, excessive adiposity was generally not associated with HSV1 or HSV2 (all p>0.05); however, there were positive correlations between HSV seroprevalence and excessive adiposity in certain age and birth cohort groups. Based on APC analysis, abdominally obese men aged 30-40 years showed a nearly 20% increase in risk for HSV1 seropositivity (adjusted prevalence ratio (aPR)=1.18; 95% CI 1.10 to 1.27) as compared with abdominally non-obese men of the same age; there was no such association in men of other age groups. Also, men of a large WC who were born before 1962 or after 1979 had a 28% higher risk for HSV2 seropositivity than those of a normal WC in the same birth cohorts (aPR=1.28, 95% CI 1.17 to 1.54); yet the association did not hold for men in other cohorts (aPR=0.86, 95% CI 0.64 to 1.17). In women, a large WC was correlated with a minimally increased HSV1 seroprevalence (aPR=1.07, 95% CI 1.01 to 1.13) but not with HSV2 seropositivity (aPR=1.13; 95% CI 0.99 to 1.28). Likewise, there were strong associations between abdominal obesity and HSV2 seropositivity in subgroups of women participating in the earliest survey cycle (aPR=1.41, 95% CI 1.12 to 1.78) but not in other survey periods (aPR=0.94, 95% CI 0.85 to 1.03).

CONCLUSIONS

There was no consistent evidence for strong associations between HSV seropositivity and excessive adiposity in adults. APC analysis results further cautioned the generalisability of previous reports based on 1 or 2 cycles of survey data.

The Effects of Combined Exercise on Health-Related Fitness, Endotoxin, and Immune Function of Postmenopausal Women with Abdominal Obesity

This study was conducted to examine the effects of combined exercise on health-related fitness, endotoxin concentrations, and immune functions of postmenopausal women with abdominal obesity. 20 voluntary participants were recruited and they were randomly allocated to the combined exercise group (n = 10) or the control group (n = 10). Visceral obesity was defined as a visceral-to-subcutaneous fat ratio ≥ 0.4 based on computed tomography (CT) results. Body composition, exercise stress testing, fitness measurement, CT scan, and blood variables were analyzed to elucidate the effects of combined exercise. The SPSS Statistics 18.0 program was used to calculate means and standard deviations for all variables. Significant differences between the exercise group and control group were determined with 2-way ANOVA and paired t-tests. The exercise group's abdominal obesity was mitigated due to visceral fat reduction; grip strength, push-ups, and oxygen uptake per weight improved; and HDL-C and IgA level also increased, while TNF-α, CD14, and endotoxin levels decreased. Lowered TNF-α after exercise might have an important role in the obesity reduction. Therefore, we can conclude that combined exercise is effective in mitigating abdominal obesity, preventing metabolic diseases, and enhancing immune function.

Biliverdin reductase isozymes in metabolism

The biliverdin reductase (BVR) isozymes BVRA and BVRB are cell surface membrane receptors with pleiotropic functions. This review compares, for the first time, the structural and functional differences between the isozymes. They reduce biliverdin, a byproduct of heme catabolism, to bilirubin, display kinase activity, and BVRA, but not BVRB, can act as a transcription factor. The binding motifs present in the BVR isozymes allow a wide range of interactions with components of metabolically important signaling pathways such as the insulin receptor kinase cascades, protein kinases (PKs), and inflammatory mediators. In addition, serum bilirubin levels have been negatively associated with abdominal obesity and hypertriglyceridemia. We discuss the roles of the BVR isozymes in metabolism and their potential as therapeutic targets.

Docosahexaenoic acid-enriched canola oil increases adiponectin concentrations: a randomized crossover controlled intervention trial

BACKGROUND AND AIMS

Little is known about the effect of various dietary fatty acids on pro- and anti-inflammatory processes. We investigated the effect of 5 oils containing various amounts of alpha-linolenic acid (ALA), linoleic acid (LA), oleic acid (OA) and docosahexaenoic acid (DHA) on plasma inflammatory biomarkers and expression levels of key inflammatory genes and transcription factors in whole blood cells.

METHODS AND RESULTS

In a randomized, crossover controlled nutrition intervention, 114 adult men and women with abdominal obesity and at least one other criterion for the metabolic syndrome consumed 5 experimental isoenergetic diets for 4 weeks each, separated by 4-week washout periods. Each diet provided 60 g/3000 kcal of different oils: 1) control corn/safflower oil blend (CornSaff; LA-rich), 2) flax/safflower oil blend (FlaxSaff; ALA-rich), 3) conventional canola oil (Canola; OA-rich), 4) high oleic canola oil (CanolaOleic; highest OA content), 5) DHA-enriched high oleic canola oil (CanolaDHA; OA- and DHA-rich). Gene expression in whole blood cells was assessed in a subset of 62 subjects. CanolaDHA increased plasma adiponectin concentrations compared with the control CornSaff oil treatment (+4.5%, P = 0.04) and FlaxSaff (+6.9%, P = 0.0008). CanolaDHA also reduced relative expression levels of interleukin (IL)1B compared with CornSaff and Canola (-11% and -13%, respectively, both P = 0.03). High-sensitivity C-reactive protein concentrations were lower after Canola than after FlaxSaff (-17.8%, P = 0.047).

CONCLUSION

DHA-enriched canola oil exerts anti-inflammatory effects compared with polyunsaturated fatty acids from plant sources.

Waist-to-height ratio, inflammation and CVD risk in obese children

OBJECTIVE

To evaluate the association between waist-to-height ratio (WHtR) and specific biomarkers of inflammation, CVD risk and endothelial dysfunction in prepubertal obese children.

DESIGN

Prospective, multicentre case-control study matched by age and sex.

SETTING

Children were recruited between May 2007 and May 2010 from primary-care centres and schools in three cities in Spain (Cordoba, Santiago de Compostela and Zaragoza).

SUBJECTS

Four hundred and forty-six (223 normal weight and 223 obese) Caucasian prepubertal children aged 6-12 years.

RESULTS

WHtR was higher in the obese than in the normal-weight children. Blood pressure, waist circumference, weight, height, insulin, plasma lipids, leptin, resistin, abnormal neutrophil and monocyte counts, C-reactive protein, IL-6, IL-8, TNF-α, myeloperoxidase, soluble intercellular adhesion molecule-1, selectin and plasminogen activator inhibitor-1 levels were higher in the obese than in the normal-weight group. Adiponectin and HDL-cholesterol were lower and glucose and metalloproteinase-9 showed no differences. Resistin, TNF-α and active plasminogen activator inhibitor-1 were associated with WHtR, a sensitive indicator of central obesity.

CONCLUSIONS

Our results lead to the hypothesis that changes in biomarker levels of insulin resistance, inflammation and CVD risk before puberty might induce metabolic consequences of obesity in obese children before reaching adulthood.

Central obesity as a clinical marker of adiposopathy; increased visceral adiposity as a surrogate marker for global fat dysfunction

PURPOSE OF REVIEW

Subcutaneous adipose tissue (SAT) is often described as 'protective'. Visceral adipose tissue (VAT) is often described as 'pathologic'. However, both SAT and VAT have protective and pathologic potential, with interdependent biologic functions.

RECENT FINDINGS

Most of the body's (excess) energy is stored as fat in SAT. If during positive caloric balance, SAT does not undergo adequate adipogenesis, then excess energy may result in adipocyte hypertrophy, leading to hypoxia, immunopathies, and endocrinopathies. Energy overflow may promote accumulation of pericardial fat, perivascular fat, and myocardial fat, which may directly contribute to atherosclerotic cardiovascular disease (CVD). Lipotoxic free fatty acid delivery to nonadipose body organs (e.g. liver, muscle, and pancreas) may indirectly contribute to CVD by promoting the most common metabolic disorders encountered in clinical practice (e.g. high blood sugars, high blood pressure, and dyslipidaemia), all major CVD risk factors. Finally, SAT energy overflow may increase VAT accumulation, which is also associated with increased risk of metabolic diseases and CVD.

SUMMARY

Increased VAT is a surrogate marker for SAT dysfunction which increases waist circumference, reflecting a shared pathologic process leading to the pathogenic fat accumulation of other fat depots and fatty infiltration of nonadipose body organs. Central obesity is a clinical marker for adiposopathy.

Abdominal fat mass is associated with adaptive immune activation: the CODAM Study

Abdominal fat-related activation of the innate immune system and insulin resistance (IR) are implicated in the pathogenesis of cardiovascular diseases. Recent data support an important role of the adaptive immune system as well. In this study, we investigate the association between waist circumference and markers of systemic adaptive immune activation, and the potential mediating role of innate immune activation and/or IR herein. The study population consisted of 477 (304 men) individuals (mean age: 59.4 ± 7.0 years) in whom waist circumference, HOMA2-IR (IR derived from homeostasis model assessment), and markers of innate (C-reactive protein (CRP), interleukin (IL)-6, serum amyloid A (SAA)) and adaptive (neopterin, soluble CD25 (sCD25)) immune activation were measured. These markers were compiled into an adaptive and innate immune activation score by averaging the respective z-scores. After adjustments for age, sex, glucose metabolism, smoking status, prior cardiovascular disease, and other risk factors, waist circumference was associated with the adaptive (standardized regression coefficient β = 0.12 (95% confidence intervals: 0.04-0.20)) and the innate immune activation scores (β = 0.24 (0.17-0.31)), and with HOMA2-IR (β = 0.49 (0.42-0.56)). The innate immune activation score and HOMA2-IR were also positively associated with the adaptive immune activation score (β = 0.31 (0.21-0.40) and β = 0.11 (0.02-0.21), respectively). The association between waist circumference and the adaptive immune activation score was completely abolished when further adjusted for innate immune activation and HOMA2-IR (to β = -0.01 (-0.10-0.08)), and the specific mediation "effects" attributable to each of these variables were 58% and 42%, respectively. We conclude that abdominal obesity is associated with systemic adaptive immune activation and that innate immune activation and IR constitute independent and equally important pathways explaining this association.

Effects of thyroid autoimmunity on abdominal obesity and hyperlipidaemia

BACKGROUND

Thyroid autoimmunity has been suggested as a risk factor for atherosclerosis independent of thyroid function in several studies. The aim of this study was to investigate whether thyroid autoimmunity had any effect on hyperlipidaemia, obesity and abdominal obesity independent of thyroid function.

MATERIAL AND METHODS

184 premenopausal female patients with Hashimoto's thyroiditis (HT) and 150 healthy premenopausal female volunteers as control group (CG) were included in the study. According to thyroid function status, the patients were divided into three subgroups: overt hypothyroid patients (ohp), subclinical hypothyroid patients (shp) and euthyroid patients (ep). Body mass index (BMI), waist to hip ratios, waist circumference (WC), and serum lipid levels of all the participants were determined. These parameters of ep were compared with those of ohp, shp and CG. Relationships among thyroid stimulating hormone (TSH), thyroid autoantibodies and lipid levels were investigated.

RESULTS

There were no significant differences between serum total cholesterol and low density lipoprotein cholesterol (LDL-C) levels of ohp and ep with HT (P = 0.18, P = 0.07 respectively) and LDL-C levels of ep were higher than those of CG (P = 0.03, P = 0.042, respectively). Although TSH levels did not correlate with serum lipid levels, levels of anti-thyroid peroxidase antibody correlated with triglyceride levels and WCs (r = 0.158; P = 0.013, r = 0.128; P = 0.048 respectively) and negatively correlated with high density lipoprotein cholesterol (HDL-C) levels (r = -0.137; P = 0.031). Levels of anti-thyroglobulin antibody also correlated with triglyceride and nonHDL-C levels (r = 0.208; P = 0.007, r = 0.158; P = 0.043 respectively).

CONCLUSION

Thyroid autoimmunity may have some effects on hyperlipidaemia and abdominal obesity independent of thyroid function.

Diet-induced obesity, exogenous leptin-, and MADB106 tumor cell challenge affect tissue leukocyte distribution and serum levels of cytokines in F344 rats

The adipocyte-derived catabolic protein leptin alters cell-mediated immunity and cytokine crosstalk. This may provide new insights into the altered immune response, seen in obese individuals. Therefore, we determined the tissue distribution of immune cells in diet-induced obese (dio) and normal weight F344 rats challenged with MADB106 tumor cells or leptin. Immune cell distribution in blood (by FACS analysis) and tissues (NK cells in spleen and liver, immunohistologically) as well as pro-inflammatory cytokines (IL-6, TNF-α; by flow cytometry) were investigated in 28 normal weight and 28 dio rats (n = 4-6/group). Pro-inflammatory cytokines were increased 3-fold for IL-6 and 7-fold for TNF-α in obese animals. Higher numbers of blood monocytes and NK cells were found in obese as compared to normal weight animals. In dio rats challenged with leptin and MADB106 tumor cells, monocyte numbers were decreased as compared to the obese control animals. Immunohistochemistry revealed an altered NK cell distribution in a compartment-, treatment-, and bodyweight-specific manner. In conclusion, our data reveal a distinct distribution pattern of monocytes and NK cells in dio rats as compared to normal weight littermates and an additional modulatory effect of a leptin- and MADB106 tumor cell challenge.