The obesity paradox: an endocrine perspective

Causal relationships between body mass index, low-density lipoprotein and bone mineral density: Univariable and multivariable Mendelian randomization

SUMMARY

Utilizing the Mendelian randomization technique, this research clarifies the putative causal relationship between body mass index (BMI) andbone mineral density (BMD), and the mediating role of low-density lipoprotein (LDL). The implications of these findings present promising opportunities for enhancing our understanding of complex bone-related characteristics and disorders, offering potential directions for treatment and intervention.

OBJECTIVE

The objective of this study is to examine the correlation between BMI and BMD, while exploring the intermediary role of LDL in mediating the causal impact of BMI on BMD outcomes via Mendelian randomization.

METHODS

In this study, we employed genome-wide association study (GWAS) data on BMI, LDL, and BMD to conduct a comparative analysis using both univariate and multivariate Mendelian randomization.

RESULTS

Our study employed a two-sample Mendelian randomization design. Considering BMI as the exposure and BMD as the outcome, our results suggest that BMI may function as a potential protective factor for BMD (β = 0.05, 95% CI 1.01 to 1.09, P = 0.01). However, when treating LDL as the exposure and BMD as the outcome, our findings indicate LDL as a risk factor for BMD (β = -0.04, 95% CI 0.92 to 0.99, P = 0.04). In our multivariate Mendelian randomization (MVMR) model, the combined influence of BMI and LDL was used as the exposure for BMD outcomes. The analysis pointed towards a substantial protective effect of LDL on BMD (β = 0.08, 95% CI 0.85 to 0.97, P = 0.006). In the analysis of mediation effects, LDL was found to mediate the relationship between BMI and BMD, and the effect was calculated at (β = 0.05, 95% CI 1.052 to 1.048, P = 0.04).

CONCLUSION

Our findings suggest that BMI may be considered a protective factor for BMD, while LDL may act as a risk factor. Moreover, LDL appears to play a mediatory role in the causal influence of BMI on BMD.

Risk factors for decreased bone mineral density in patients with metabolic dysfunction-associated steatotic liver disease: A cross-sectional study at a health examination center

BACKGROUND & AIMS

Steatotic liver disease (SLD) is often detected in health examinations. However, although individuals with metabolic dysfunction-associated SLD (MASLD) may have decreased bone mineral density (BMD), the specific risk factors remain unclarified. The objective of this study was to identify the factors associated with decreased BMD in patients with MASLD.

METHODS

Individuals who underwent abdominal ultrasonography and BMD measurements at our healthcare center were included. The BMD of the calcaneus was assessed using an AOS-10SA bone densitometer. Decreased BMD was defined as a T-score below -1.0 SD or the administration of osteoporosis treatment. SLD was diagnosed based on specific ultrasonographic criteria.

RESULTS

A total of 1410 patients were diagnosed with MASLD. The median age was 52 years. Multivariate analysis using a logistic regression model revealed that the independent predictors of decreased BMD were a low body mass index (BMI) or a small waist circumference (odds ratio (OR): 0.48, 95% confidence interval (CI): 0.34-0.67), hypertriglyceridemia (OR: 1.29, 95% CI: 1.00-1.65), and a weak grip strength (OR: 0.98, 95% CI: 0.97-1.00). Subgroup analyses of individuals aged 50 years or older, men, and individuals with a FIB-4 index of 1.3 or greater revealed that the absence of a high BMI or a large waist circumference was associated with decreased BMD. The subgroup analysis of men revealed that a weaker grip strength was associated with decreased BMD.

CONCLUSION

The present study suggested several potential risk factors for decreased BMD in patients with MASLD. Individuals with the abovementioned risk factors should be encouraged to undergo BMD measurement from the perspective of preventive medicine.

A Nonlinear Relation between Body Mass Index and Long-Term Poststroke Functional Outcome-The Importance of Insulin Resistance, Inflammation, and Insulin-like Growth Factor-Binding Protein-1

Both high serum insulin-like growth factor-binding protein-1 (s-IGFBP-1) and insulin resistance (IR) are associated with poor functional outcome poststroke, whereas overweight body mass index (BMI; 25-30) is related to fewer deaths and favorable functional outcome in a phenomenon labeled "the obesity paradox". Furthermore, IGFBP-1 is inversely related to BMI, in contrast to the linear relation between IR and BMI. Here, we investigated s-IGFBP-1 and IR concerning BMI and 7-year poststroke functional outcome. We included 451 stroke patients from the Sahlgrenska Study on Ischemic Stroke (SAHLSIS) with baseline measurements of s-IGFBP1, homeostasis model assessment of IR (HOMA-IR), BMI (categories: normal-weight (8.5-25), overweight (25-30), and obesity (>30)), and high-sensitivity C-reactive protein (hs-CRP) as a measure of general inflammation. Associations with poor functional outcome (modified Rankin scale [mRS] score: 3-6) after 7 years were evaluated using multivariable binary logistic regression, with overweight as reference due to the nonlinear relationship. Both normal-weight (odds-ratio [OR] 2.32, 95% confidence interval [CI] 1.30-4.14) and obese (OR 2.25, 95% CI 1.08-4.71) patients had an increased risk of poor functional outcome, driven by deaths only in the normal-weight. In normal-weight, s-IGFBP-1 modestly attenuated (8.3%) this association. In the obese, the association was instead attenuated by HOMA-IR (22.4%) and hs-CRP (10.4%). Thus, a nonlinear relation between BMI and poor 7-year functional outcome was differently attenuated in the normal-weight and the obese.

Associations between the VDR Gene rs731236 (TaqI) Polymorphism and Bone Mineral Density in Postmenopausal Women from the RAC-OST-POL

BACKGROUND

Postmenopausal osteoporosis is not only related to hormonal factors but is also associated with environmental and genetic factors. One of the latter is the polymorphism of vitamin D receptor (VDR). The aim of the reported study was to comprehensively analyze the VDR gene polymorphic variants rs731236 (TaqI), rs1544410 (BsmI) and rs7975232 (ApaI) in the Polish population of postmenopausal women.

METHODS

The study group consisted of 611 women after menopause (their median age was 65.82 ± 6.29 years). Each of them underwent bone densitometry (DXA) of the non-dominant femoral neck and total hip with a biochemical analysis of vitamin D3 serum concentration and genotyping of the above-mentioned single nucleotide polymorphisms (SNPs); the obtained results were analyzed in the aspect of waist circumference (WC), body mass index (BMI) and past medical history.

RESULTS

The genotype prevalence rates of all SNPs were compatible with Hardy-Weinberg equilibrium (p > 0.050). Out of the studied polymorphisms, only rs731236 genotype variants affected DXA, with AG heterozygotes showing the worst bone parameters. Neither patient age nor vitamin D3 concentration, BMI, WC or comorbidities was associated with rs731236 genotype.

CONCLUSIONS

Out of the polymorphisms studied, only rs731236 genotypes differed among the DXA results, while the AG heterozygotes were characterized by the lowest median bone mineral density.

Obesity, diabetes and risk of bone fragility: How BMAT behavior is affected by metabolic disturbances and its influence on bone health

PURPOSE

Osteoporosis is a metabolic bone disease characterized by decreased bone strength and mass, which predisposes patients to fractures and is associated with high morbidity and mortality. Like osteoporosis, obesity and diabetes are systemic metabolic diseases associated with modifiable risk factors and lifestyle, and their prevalence is increasing. They are related to decreased quality of life, functional loss and increased mortality, generating high costs for health systems and representing a worldwide public health problem. Growing evidence reinforces the role of bone marrow adipose tissue (BMAT) as an influential factor in the bone microenvironment and systemic metabolism. Given the impact of obesity and diabetes on metabolism and their possible effect on the bone microenvironment, changes in BMAT behavior may explain the risk of developing osteoporosis in the presence of these comorbidities.

METHODS

This study reviewed the scientific literature on the behavior of BMAT in pathological metabolic conditions, such as obesity and diabetes, and its potential involvement in the pathogenesis of bone fragility.

RESULTS

Published data strongly suggest a relationship between increased BMAT adiposity and the risk of bone fragility in the context of obesity and diabetes.

CONCLUSION

By secreting a broad range of factors, BMAT modulates the bone microenvironment and metabolism, ultimately affecting skeletal health. A better understanding of the relationship between BMAT expansion and metabolic disturbances observed in diabetic and obese patients will help to identify regulatory pathways and new targets for the treatment of bone-related diseases, with BMAT as a potential therapeutic target.

Strong Association of Metabolic Parameters with ADMA and VCAM-1 in Normo-Weight Subjects with Metabolic Syndrome

Background

Metabolic syndrome (MetS) is a risk factor for cardiovascular disease and is linked to obesity. Subjects with MetS who have normo-weight potentially show higher mortality and morbidity.

Purpose

This study aims to reveal the critical essential metabolic parameters associated with endothelial dysfunction in MetS subjects with normo-weight compared to obese.

Patients and Methods

The study was designed using a case-control approach. Ninety-nine MetS subjects (34 Normo-weight and 65 obese) from the urban population were enrolled in this study. The components of MetS are based on NCEP/ATP III criteria. Asymmetric dimethylarginine (ADMA) and vascular cell adhesion molecule 1 (VCAM-1) as markers for endothelial dysfunction were measured in both groups.

Results

Fasting blood glucose (FBG) levels were higher in the normo-weight group (143.38 ± 79.8 mg/dL) compared to the obese group (120.89 ± 46.5 mg/dL). High-density lipoprotein cholesterol (HDL-c) levels in the normo-weight group were lower (42.82 ± 10.1 mg/dL) compared to obesity (45.74 ± 9.3 mg/dL), while triacylglycerol (TAG) levels were higher in the obese (197.25 ± 110.5 mg/dL) compared to the normo-weight group (167.03 ± 98.4 mg/dL), although the differences were statistically not significant (all p > 0.05). The difference between ADMA and VCAM-1 levels was statistically not significant in both groups. Correlation between MetS components with endothelial dysfunction parameters shows that metabolic parameters correlate strongly. Interestingly, a stronger correlation between FBG and ADMA was observed in normo-weight (r = 0.519) compared to obese groups (r = 0.445). In addition, TAG consistently shows a significant correlation with ADMA and VCAM-1 in normo-weight groups.

Conclusion

Metabolic parameters, especially FBG and TAG, correlate strongly with endothelial dysfunction parameters in normo-weight subjects with metabolic syndrome.

Effects of environmentally relevant concentrations of niclosamide on lipid metabolism and steroid hormone synthesis in adult female zebrafish

Niclosamide (NIC) is a commonly used molluscicide that reportedly disrupts the endocrine system and may lead to lipid metabolism disorders. However, few studies have investigated the mechanism by which NIC affects the endocrine system from the perspective of lipid metabolism. Adult female zebrafish were fed either a normal-fat diet (NFD) or a high-fat diet (HFD) and then exposed for 28 days to environmentally relevant concentrations of NIC. NIC accumulated most in the liver followed by the brain and then the gonads in both feeding conditions. Somatic index changes confirmed that HFD promotes fish growth, and NIC administration inhibits it. Lipid metabolites were decreased by NIC, as were levels of pregnenolone, androstenedione, estrogen, testosterone, and estradiol, suggesting that NIC impacted steroidogenesis. In addition, gene transcription changes related to the hypothalamic-pituitary-gonad-liver (HPGL) axis and altered ovarian histology strongly suggest that environmental relevant concentrations of NIC exposure may disrupt endocrine function. These findings highlighted that NIC exposure at environmentally relevant concentrations elicited endocrine-disruption effects may through impairing of steroid hormone synthesis.

Role of obesity in pathogenesis of acute pancreatitis

Acute pancreatitis (AP) is one of the most common digestive disorders that cause hospitalization. While most of patients with AP have a mild to moderate disease and recover rapidly, about 20% of patients with AP have a severe disease and experience substantial morbidity and mortality from local and/or systemic compli-cations. The incidence of obesity has increased worldwide, and its epidemiological characteristics and rising trend are consistent with those of AP. Therefore, obesity has probably contributed to the increase in the incidence and severity of AP. However, previous studies have generated conflicting results, and some studies demonstrated that obesity is a protective factor in patients with AP. Here we discuss the role of obesity in the pathogenesis of AP and the underlying mechanisms based on clinically relevant studies.

Association between body fat and bone mineral density in Korean adults: a cohort study

Although obesity was once considered protective against osteoporosis, various factors influence the relationship between fat and bone mineral density (BMD). To establish the importance of healthy body composition in decelerating declines in BMD, we conducted a study to compare the association between body fat composition and BMD in Korean adults. Using data collected from the Kangbuk Samsung Health Study from 2012 to 2019, this cohort study compared the incidence of decreased BMD among the following four groups: normal BMI and normal adiposity (NBMI-NA), normal BMI and high adiposity (NBMI-HA), overweight, and obesity. Decreased BMD was defined as a Z-score ≤  - 2.0 in premenopausal women and men < 50 years of age or a T-score <  - 1.0 in postmenopausal women and men ≥ 50 years of age. Individuals who were diagnosed with osteoporosis or compression fracture after their second visit were categorized as having decreased BMD. The incidence rate of decreased BMD in the NBMI-NA group was 3.37, and that in the NBMI-HA group was 4.81, which was the highest among all groups. After adjusting for confounding factors, NBMI-HA led to a significantly greater risk of decreased BMD compared to NBMI-NA (HR 1.47; 95% CI 1.09-1.99). Even with a normal BMI, a high BFP was associated with an increased risk of decreased BMD. Therefore, healthy body composition management, not simply BMI, is important in preventing decreased BMD.

Subtyping patients with chronic disease using longitudinal BMI patterns

Obesity is a major health problem, increasing the risk of various major chronic diseases, such as diabetes, cancer, and stroke. While the role of obesity identified by cross-sectional BMI recordings has been heavily studied, the role of BMI trajectories is much less explored. In this study, we use a machine learning approach to subtype individuals' risk of developing 18 major chronic diseases by using their BMI trajectories extracted from a large and geographically diverse EHR dataset capturing the health status of around two million individuals for a period of six years. We define nine new interpretable and evidence-based variables based on the BMI trajectories to cluster the patients into subgroups using the k-means clustering method. We thoroughly review each cluster's characteristics in terms of demographic, socioeconomic, and physiological measurement variables to specify the distinct properties of the patients in the clusters. In our experiments, the direct relationship of obesity with diabetes, hypertension, Alzheimer's, and dementia has been re-established and distinct clusters with specific characteristics for several of the chronic diseases have been found to be conforming or complementary to the existing body of knowledge.

Association of Body Compositions and Bone Mineral Density in Chinese Children and Adolescents: Compositional Data Analysis

The purpose of this study was to investigate the relationship between body compositions and bone mineral density (BMD) and the effect of composition substitution among Chinese children and adolescents without the influence of multicollinearity. A dual-energy X-ray absorptiometry scan was used to determine the amount of truncal fat (TF), nontruncal fat (NTF), fat-free mass (FFM), and BMD. The compositional data analysis and the compositional proportional substitution analysis were conducted to determine the effect of each part of body compositions on BMD and its substitution effects. Four hundred sixty-six (466) (boys: 51.9%) participants completed this cross-sectional study. For girls, in the overweight group, the relationship between TF and the BMD was positive (β = 2.943e - 01, p = 0.006) while the NTF showed the opposite trend (β = -2.358e - 01, p = 0.009). When 4% NTF or FFM was substituted by TF, the BMD increased by about 0.1 and 0.05 units (p < 0.05), respectively. For boys, the association between FFM and BMD was statistically positive (β = 4.091e - 02, p = 0.0001). There was a positive correlation between TF and BMD (β = 7.963e - 02, p = 0.036). But with the increase of BMI, this correlation shifted in the opposite direction. In conclusion, compared to TF and NTF, FFM had a better protective effect on BMD, especially for boys. The risk of NTF accumulation on BMD was greater than that of TF accumulation. Compared with girls, boys were more sensitive to the amount of TF.

Associations of accumulated selected persistent organic pollutants in adipose tissue with insulin sensitivity and risk of incident type-2 diabetes

Continuous exposure to low doses of persistent organic pollutant (POPs), such as those occurring in the general population, might contribute to the burden of type 2 diabetes mellitus (T2DM). However, evidences from longitudinal studies are scarce. We aimed to explore the associations of accumulated POP exposure with the development of T2DM by means of 1) longitudinal associations with the 16-year incidence of the disease, and 2) complementary cross-sectional analyses with markers of glucose homeostasis at recruitment. Organochlorine pesticide and polychlorinated biphenyl (PCB) concentrations were analyzed in adipose tissue samples and incident T2DM cases were retrieved from clinical records. Homeostatic model assessment values of insulin sensitivity/resistance and β-cell function at recruitment were calculated. Linear and Cox-regression models were performed. In individuals with normal weight/overweight (n = 293), we observed positive dose-response relationships between the studied POPs and T2DM risk, particularly for hexachlorobenzene (HCB) [hazard ratio (HR): 3.96 for 4th quartile versus 1st quartile (Q1); confidence interval (CI) 95%: 0.79, 19.71]. PCB-180 showed a positive but seemingly non-linear association with T2DM risk [HR of 3^er quartile (Q3) versus Q1: 6.48; CI 95%: 0.82, 51.29]. Unadjustment for body mass index considerably increased the magnitude of the associations. In the cross-sectional study (n = 180), HCB and PCB-180 were inversely associated with insulin sensitivity and positively associated with insulin resistance parameters. Our results suggest that a higher burden of specific POPs in adipose tissue may disrupt glucose homeostasis, possibly contributing to increase T2DM risk, especially in non-obese adults.

Low body mass index is associated with increased mortality in patients with pelvic and acetabular fractures

AIMS

Fractures of the pelvis and acetabulum are often the consequence of high energy trauma in young individuals or fragility fractures in osteoporotic bone. They can be life-threatening or life changing injuries. No published data exists comparing body mass index (BMI) and mortality for this patient group. The aim of this study was to identify if low BMI (<18.5) was a predictor of morbidity and mortality for patients with these injuries.

PATIENTS AND METHODS

Of the 1033 patients with pelvic or acetabular fractures referred to a single level 1 major trauma centre (MTC) over a 4.5-year period (August 2015 - January 2020); we retrospectively analysed data for all admitted patients. Data was collected on demographics, injury pattern, operative intervention and complications. Comparison was made between patients that were underweight (BMI<18.5) and patients that were not. Both in-hospital and post discharge complications were recorded including pulmonary embolus (PE), deep venous thrombosis (DVT), ileus, infection, loss of reduction and mortality at 6 months.

RESULTS

569 patients admitted to the MTC with a pelvic or acetabular fracture were included in our analysis. Underweight patients had a statistically significant increase in mortality both in-hospital (p = 0.019) and at 6 months post injury (p = 0.039) when compared to other BMI groups. No statistical significance was found between these BMI groups comparing morbidity: DVT (p = 0.712), PE (p = 0.736) nor ileus (p = 0.149). Covariate analysis showed that a low BMI was associated with triple the in-hospital mortality after correction for age and energy of injury (adjusted OR 3.028, 95% CI 1.059-8.659).

CONCLUSION

This is the first published study that demonstrates a statistically significant increase in mortality in patients with pelvic or acetabular fractures who are underweight. Surgeons should carefully consider appropriate peri-operative optimisation for these patients. Further investigation into the effects of low BMI and response to trauma is required.

Periodontitis is an inflammatory disease of oxidative stress: We should treat it that way

Periodontitis is a highly prevalent disease. As it progresses, it causes serious morbidity in the form of periodontal abscesses and tooth loss and, in the latter stages, pain. It is also now known that periodontitis is strongly associated with several nonoral diseases. Thus, patients with periodontitis are at greater risk for the development and/or exacerbation of diabetes, chronic obstructive pulmonary disease, and cardiovascular diseases, among other conditions. Although it is without question that specific groups of oral bacteria which populate dental plaque play a causative role in the development of periodontitis, it is now thought that once this disease has been triggered, other factors play an equal, and possibly more important, role in its progression, particularly in severe cases or in cases that prove difficult to treat. In this regard, we allude to the host response, specifically the notion that the host, once infected with oral periodontal pathogenic bacteria, will mount a defense response mediated largely through the innate immune system. The most abundant cell type of the innate immune system - polymorphonuclear neutrophils - can, when protecting the host from microbial invasion, mount a response that includes upregulation of proinflammatory cytokines, matrix metalloproteinases, and reactive oxygen species, all of which then contribute to the tissue damage and loss of teeth commonly associated with periodontitis. Of the mechanisms referred to here, we suggest that upregulation of reactive oxygen species might play one of the most important roles in the establishment and progression of periodontitis (as well as in other diseases of inflammation) through the development of oxidative stress. In this overview, we discuss both innate and epigenetic factors (eg, diabetes, smoking) that lead to the development of oxidative stress. This oxidative stress then provides an environment conducive to the destructive processes observed in periodontitis. Therefore, we shall describe some of the fundamental characteristics of oxidative stress and its effects on the periodontium, discuss the diseases and other factors that cause oxidative stress, and, finally, review potentially novel therapeutic approaches for the management (and possibly even the reversal) of periodontitis, which rely on the use of therapies, such as resveratrol and other antioxidants, that provide increased antioxidant activity in the host.

Associations of Weight-Adjusted Body Fat and Fat Distribution with Bone Mineral Density in Chinese Children Aged 6-10 Years

Although obesity is considered osteoprotective, the effects of body fat and fat distribution on bone tissue after adjusting for the effects of body weight remain uncertain. This study evaluated the relationships between fat mass, fat distribution, and bone mineral status beyond its weight-bearing effect. We recruited 466 children aged 6–10 years in China. Dual-energy X-ray absorptiometry was used to determine the bone mineral density (BMD) and bone mineral content (BMC) in the total body and total body less head (TBLH), as well as the fat mass (FM) and percentage fat mass (%FM) of the total and segmental body. Weight-adjusted measures of FM and %FM were derived using the residual method. After adjusting for the effects of covariates, we observed statistically significant, dose-dependent negative relationships between the TBLH·BMD/BMC and various weight-adjusted measures of body fat (p for trend: <0.001–0.038). For each standard deviation increment in the weight-adjusted total body, TBLH, trunk and limbs, the size-adjusted BMC decreased approximately 9.44, 9.28, 8.13, and 6.65 g in boys, respectively, and by approximately 13.74, 13.71, 7.84, and 12.95 g in girls, respectively. Significant inverse associations between FM accumulation in the total body and most body parts with the BMD/BMC were observed in both boys and girls after adjusting for weight and potential confounders.

Low psoas muscle index associates with long-term mortality in cirrhosis: construction of a nomogram

Background

To develop a nomogram incorporating indicator of muscle waste to prognosticate long-term mortality in liver cirrhosis (LC), and identify the prognostic impact of psoas muscle index (PMI).

Methods

A total of 251 LC patients who underwent computed tomography were included in this study. Multiple Cox regression was performed, and sex-specific nomogram models incorporating PMI were developed. The utility of the proposed models were evaluated by Harrell’s concordance index (C-index), calibration curve and decision curve analysis. X-tile was used to determine optimal cutpoint for stratifying subjects with distinct outcomes. Subgroup analysis was implemented in terms of age and MELD score. The correlation between PMI and gait speed was also evaluated.

Results

On multiple analysis, independent predictors for 3-year all-cause mortality were age, BMI, PMI and MELD for males, and age, PMI and MELD for females. Both nomogram models gave rise to moderately strong discrimination, with a C-index of 0.792 (95% CI: 0.723–0.861) in males and 0.715 (95% CI: 0.637–0.793) in females, respectively. The calibration curve implied predicted survival corresponding optimally with the actual outcomes. The proposed models were feasible in clinical settings based on decision curve analysis. On subgroup analysis, PMI might confer valid predictive value on LC patients with MELD <15. Moreover, a definitely positive correlation between PMI and gait speed was revealed.

Conclusions

Our proposed nomogram embedding PMI rendered an individualized predictive tool for long-term mortality in LC. The diminishing value of PMI is likely indicative of muscle dysfunction.

Pathobiological mechanisms underlying metabolic syndrome (MetS) in chronic obstructive pulmonary disease (COPD): clinical significance and therapeutic strategies

Chronic obstructive pulmonary disease (COPD) is a major incurable global health burden and is currently the 4th largest cause of death in the world. Importantly, much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities (e.g. skeletal muscle wasting, ischemic heart disease, cognitive dysfunction) and infective viral and bacterial acute exacerbations (AECOPD). Current pharmacological treatments for COPD are relatively ineffective and the development of effective therapies has been severely hampered by the lack of understanding of the mechanisms and mediators underlying COPD. Since comorbidities have a tremendous impact on the prognosis and severity of COPD, the 2015 American Thoracic Society/European Respiratory Society (ATS/ERS) Research Statement on COPD urgently called for studies to elucidate the pathobiological mechanisms linking COPD to its comorbidities. It is now emerging that up to 50% of COPD patients have metabolic syndrome (MetS) as a comorbidity. It is currently not clear whether metabolic syndrome is an independent co-existing condition or a direct consequence of the progressive lung pathology in COPD patients. As MetS has important clinical implications on COPD outcomes, identification of disease mechanisms linking COPD to MetS is the key to effective therapy. In this comprehensive review, we discuss the potential mechanisms linking MetS to COPD and hence plausible therapeutic strategies to treat this debilitating comorbidity of COPD.

Low subcutaneous adiposity associates with higher mortality in female patients with cirrhosis

BACKGROUND & AIMS

Two major body compartments, skeletal muscle and adipose tissue, exhibit independent functions. We aimed to explore the prognostic significance of skeletal muscle, visceral and subcutaneous adipose tissue, according to sex, in patients with cirrhosis assessed for liver transplantation (LT).

METHODS

CT images taken at the 3rd lumbar vertebra from 677 patients were quantified for three body composition indexes (cm²/m²), visceral adipose tissue index, subcutaneous adipose tissue index (SATI), and skeletal muscle index (SMI). Cox proportional and competing-risk analysis hazard models were conducted to assess associations between mortality and body composition.

RESULTS

The majority of patients were male (67%) with a mean age of 57 ± 7 years, model for end-stage liver disease (MELD) score of 14 ± 8 and mean body mass index of 27 ± 6 kg/m². Despite similar body mass index between the sexes, male patients had greater SMI (53 ± 12 vs. 45 ± 9 cm²/m²), whereas SATI (67 ± 52 vs. 48 ± 37 cm²/m²) was higher in females (p <0.001 for each). In sex stratified multivariate analyses after adjustment for MELD score and other confounding variables, SATI in females (hazard ratio [HR] 0.99; 95% CI 0.98-1.00; p = 0.01) and SMI in males (HR 0.98; 95% CI 0.96-1.00; p = 0.02) were significant predictors of mortality. Female patients with low SATI (<60 cm²/m²) had a higher risk of mortality (HR 2.06; 95% CI 1.08-3.91; p = 0.03). Using competitive risk analysis in female patients listed for LT, low SATI was also an independent predictor of mortality (subdistribution HR 2.80; 95% CI 1.28-6.12; p = 0.01) after adjusting for MELD, and other confounding factors.

CONCLUSIONS

A lower SATI is associated with higher mortality in female patients with cirrhosis. Subcutaneous adipose tissue has a favorable metabolic profile - low SATI may reflect depletion of this major energy reservoir, leading to poor clinical outcomes.

LAY SUMMARY

We looked at the importance of two of the main body compartments, skeletal muscle and adipose tissue (fat) on the prognosis of males and females with end-stage liver disease. Lower amounts of subcutaneous fat but not visceral fat (around internal organs), are associated with higher mortality in female patients with end-stage liver disease. However, low skeletal muscle predicts mortality in male patients with end-stage liver disease.

The obesity paradox and osteoporosis

Overweight and obesity according to the definition of the WHO are considered as an abnormal or excessive fat accumulation that may impair health. Studies comparing fracture incidence in obese and non-obese individuals have demonstrated that obesity, defined on the basis of body mass index (BMI), is associated with increased risk of fracture at some sites but seems to be protective at others. The results of the studies are influenced by the distribution of BMI in the population studied; for example, in cohorts with a low prevalence of obesity, a predilection for certain fracture sites in obese individuals becomes difficult to detect, whereas, in populations with a high prevalence of obesity, previously unreported associations may emerge. Furthermore, obesity can bring with itself many complications (Type 2 diabetes mellitus, vitamin D deficiency, and motor disability) which, in the long run, can have a definite influence in terms of overall risk and quality of life, as well. This is a narrative review focusing on the relationship between bone metabolism and overweight/obesity and dealing with the fundamental dilemma of a disease (obesity) apparently associated with improved values of bone mineral density, part of a complicated relationship which revolves around obesity called "the obesity paradox".

The burden of obesity in asthma and COPD: Role of adiponectin

The influence of obesity on development, severity and prognosis of both asthma and COPD is attracting growing interest. The impact of obesity on the respiratory system ranges from structural modifications (decline of total lung capacity) to humoral alterations. Adipose tissue strongly contributes to the establishment of an inflammatory state being an important source of adipokines. Amongst adipokines, adiponectin is an important component of organ cross talk with adipose tissue exerting protective effects on a variety of pathophysiological processes. Adiponectin is secreted in serum where it abundantly circulates as complexes of different molecular weight. Adiponectin properties are mediated by specific receptors that are widely expressed with AdipoR1, AdipoR2, and T-cadherin being present on epithelial and endothelial pulmonary cells indicating a functional role on lung physiology. In COPD, mild to moderate obesity has been shown to have protective effects on patient's survival, while a higher mortality rate has been observed in patients with low BMI. A specific cluster of obese patients has been identified; in this group, asthma features are particularly severe and difficult to treat. Better understanding of the molecular mechanisms at the base of cross talk among different tissues and organs will lead to identification of new targets for both diagnosis and treatment of asthma and COPD.

Inability to replete white adipose tissue during recovery phase of sepsis is associated with increased autophagy, apoptosis, and proteasome activity

Adipose tissue is an important energy depot and endocrine organ, and the degree of adiposity impacts the host response to infection. However, little is known regarding the mechanisms by which white adipose tissue (WAT) is lost acutely and then restored after the resolution of sepsis. Therefore, the signaling pathways governing protein synthesis, autophagy, apoptosis, and the ubiquitin-proteasome were investigated to identify potential mechanisms mediating the acute (24 h) loss of WAT after cecal ligation and puncture as well as the failure to replenish WAT during recovery (day 10). While whole body fat mass was decreased equally in pair-fed control and septic mice at 5 days after cecal ligation and puncture, fat mass remained 35% lower in septic mice at day 10 During sepsis-recovery, protein synthesis in epididymal WAT was increased compared with control values, and this increase was associated with an elevation in eukaryotic translation initiation factor (eIF)2Bε but no change in mammalian target of rapamycin complex 1 activity (eIF4E-binding protein-1 or S6 kinase 1 phosphorylation). Protein breakdown was increased during sepsis-recovery, as evidenced by the elevation in ubiquitin-proteasome activity. Moreover, indexes of autophagy (light chain 3B-II, autophagy-related protein 5/12, and beclin) were increased during sepsis-recovery and associated with increased AMP-activated kinase-dependent Ser⁵⁵⁵-phosphorylated Unc-51-like autophagy activating kinase-1. Apoptosis was increased, as suggested by the increased cleavage of caspase-3 and poly(ADP-ribose) polymerase. These changes were associated with increased inflammasome activity (increased NLR family, pyrin domain containing 3; TMS1; and caspase-1 cleavage) and the endoplasmic reticulum stress response (increased eIF2α and activating transcription factor-4) and browning (uncoupling protein-1) in epididymal WAT. Our data suggest that WAT stores remain depleted during recovery from sepsis due to sustained inflammation and elevations in protein and cellular degradation, despite the increase in protein synthesis.