Association of normal weight obesity phenotype with inflammatory markers: A systematic review and meta-analysis

Bridging the gap in obesity research: A consensus statement from the European Society for Clinical Investigation

BACKGROUND

Most forms of obesity are associated with chronic diseases that remain a global public health challenge.

AIMS

Despite significant advancements in understanding its pathophysiology, effective management of obesity is hindered by the persistence of knowledge gaps in epidemiology, phenotypic heterogeneity and policy implementation.

MATERIALS AND METHODS

This consensus statement by the European Society for Clinical Investigation identifies eight critical areas requiring urgent attention. Key gaps include insufficient long-term data on obesity trends, the inadequacy of body mass index (BMI) as a sole diagnostic measure, and insufficient recognition of phenotypic diversity in obesity-related cardiometabolic risks. Moreover, the socio-economic drivers of obesity and its transition across phenotypes remain poorly understood.

RESULTS

The syndemic nature of obesity, exacerbated by globalization and environmental changes, necessitates a holistic approach integrating global frameworks and community-level interventions. This statement advocates for leveraging emerging technologies, such as artificial intelligence, to refine predictive models and address phenotypic variability. It underscores the importance of collaborative efforts among scientists, policymakers, and stakeholders to create tailored interventions and enduring policies.

DISCUSSION

The consensus highlights the need for harmonizing anthropometric and biochemical markers, fostering inclusive public health narratives and combating stigma associated with obesity. By addressing these gaps, this initiative aims to advance research, improve prevention strategies and optimize care delivery for people living with obesity.

CONCLUSION

This collaborative effort marks a decisive step towards mitigating the obesity epidemic and its profound impact on global health systems. Ultimately, obesity should be considered as being largely the consequence of a socio-economic model not compatible with optimal human health.

Cytokine atlas of the population-based cohort SHIP-TREND-0 - Associations with age, sex, and BMI

BACKGROUND

The characterization of physiological immune signatures in a population-based cohort is a prerequisite for identifying pathological immune signatures associated with inflammatory or autoimmune diseases.

METHODS

Here, 47 plasma cytokines, chemokines, and growth factors were quantified with a bead-based multiplex-assay (Merck HCYTA-60 K) using a FLEXMAP 3D™ instrument in 1175 individuals of the Study of Health in Pomerania (SHIP; TREND cohort, 532 men and 643 women, age: 20 to 81, BMI: 17.7 to 53.6). Associations of cytokine concentrations with age, sex, BMI, season, and blood cell parameters (BCP) were examined by multivariate regression models.

RESULTS

The physiological cytokine concentrations differed strongly between analytes, with median concentrations ranging from 0.6 to 7820 pg/mL. Many cytokine levels showed a large dynamic range within the study population. Higher levels of the pro-inflammatory cytokines and chemokines IL-6, IL-8, CXCL9, CXCL10, IL-12p40, CCL2, CCL4, CCL11, IL-27, FLT3LG, and TNFα were significantly associated with increasing age. The strongest age-associated effects were seen for CXCL9 (βst = 0.4, p < 0.001) and CXLC10 (βst = 0.3, p < 0.001). Significant sex differences were detected for CCL2, CCL3, CCL4, CCL11, CCL22, IL-12p40, IL-1RA, IL-18, IL-27, and TNFα levels among which CCL11 showed the strongest effect (βst = -0.24, p < 0.001) with a lower level in women compared to men. Moreover, seven cytokines and chemokines, i.e. CCL4, CCL22, CXCL10, IL-1RA, IL-18, IL-6, and TNFα, displayed higher levels with increasing BMI. Among those, the strongest effect was seen for IL-1RA (βst = 0.19, p < 0.001), CCL4 (βst = 0.16, p < 0.001) and CXCL10 (βst = 0.14, p < 0.001). Only CCL11 (βst = -0.17, p < 0.001) decreased with increasing BMI. Subjects categorized as obese exhibited significantly elevated levels of CCL4, CCL22, CXCL10, and IL-1RA, while only CCL11 showed significantly reduced levels compared to normal weight. Certain cytokines such as IL-6, IL-18, or TNFα showed decreased significance levels after adjustment for blood cell components indicating blood cell components (BCPs) as potential confounders. We observed no significant non-linear seasonal effects for the investigated cytokines.

CONCLUSION

The generated cytokine atlas provides detailed information on cytokine variations in the general population and will provide a reference base for disease-related studies in the future. Furthermore, BCPs should be considered as potential confounders in association studies based on plasma cytokine levels.

Adolescents with Normal Weight Obesity Have Less Dry Lean Mass Compared to Obese Counterparts

Normal weight obesity (NWO) is a condition characterized by a normal body mass index (BMI; 18.5-24.9 kg·m-2) yet excess body fat. Those with this condition have an increased risk of cardiometabolic diseases associated with obesity. The prevalence of NWO is not well investigated in adolescents, particularly in the United States. This study examined the prevalence of NWO and dietary behaviors among adolescents aged 14-19 years old (n = 139) who live in a rural area in the United States. Data were collected from December 2019 through February 2020. Body composition was assessed via bioelectrical impedance analysis and diet was assessed using an Automated Self-Administered 24 h food recall questionnaire. Participants were categorized by BMI and body fat percentage as NWO, normal weight lean (NWL), or obese (OB). The sample prevalence of NWO was 13.6%, with girls having a higher prevalence (22.2%) than boys (1.8%). Those with NWO had significantly lower dry lean mass than OB (p = 0.02), but there were no differences between NWL and OB (p = 0.08). There was significantly higher caloric intake (p = 0.02) among NWL compared to OB, and NWL consumed more fiber than both NWO (p = 0.02) and OB (p = 0.03). Overall, this study gives us a better understanding of the prevalence of NWO in the adolescent population and the dietary habits associated with each group. Those with NWO may be at increased risk for negative long-term health outcomes commonly associated with obesity. Additionally, the higher caloric intake among NWL was unexpected and should be investigated further.

Association between normal weight obesity and comorbidities and events of cardiovascular diseases among adults in South China

BACKGROUND

The increased risks for cardiovascular comorbidities and cardiovascular diseases (CVD) in populations with normal weight obesity (NWO) have not been well-identified. We aimed to study their associations in an adult population in South China.

METHODS

Based on the CVD prevalence of 4% in Shenzhen and a calculated sample size of 6,000, a cross-sectional study with a multi-stage stratified cluster sampling method was conducted in Shenzhen City. The cardiovascular comorbidities being studied were abdominal obesity (AO), diabetes, hypertension, dyslipidemia, metabolic syndrome, and chronic kidney disease, while the CVD events were occurrences of myocardial infarction and strokes. Questionnaire surveys, physical examinations, and laboratory tests were performed. NWO was defined as a condition with the highest tertile of body fat percentage (BF%) among the normal body mass index (BMI) range (18.5-23.9 kg/m2). Continuous data were reported as mean [standard deviation (SD)] and categorical data as percentages (%). CVD comorbidities and CVD events and their detection rates in different groups were compared using ANONA analysis and Chi-squared test. Spearman's correlation coefficients between BF% and cardiometabolic abnormalities were calculated by partial correlation analysis. Multivariate logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for BF%, CVD comorbidities, and CVD events, adjusted for multiple confounders.

RESULTS

Among the total 6,240 subjects who completed the study and had BMI and BF% data available, 3,086 had normal BMI. The prevalence of NWO was 16.36%, with 13.15% for men and 19.54% for women. With confounders adjusted, the risks of AO (OR = 6.05, 95%CI = 3.40-10.75), essential hypertension (OR = 1.56, 95%CI = 1.09-2.22), dyslipidemia (OR = 1.85, 95%CI = 1.49-2.29), and metabolic syndrome (OR = 4.61, 95%CI = 2.32-9.18) were significantly increased in the populations with NWO compared with the population without NWO (P < 0.05). BF% was not significantly associated with the risk of CVD events in the total (OR = 1.56, 95%CI = 0.83-2.93), male (OR = 1.00, 95%CI = 0.44-2.30), and female populations (OR = 2.53, 95%CI = 0.91-7.06).

CONCLUSION

NWO was found to be positively associated with CVD comorbidities but not with CVD events. The current study provides a ground to conduct further studies on whether body fat affects the risk of occurrence of CVD events and the underlying mechanisms in the future.

Association between inflammatory markers, body composition and frailty in home-dwelling elderly: an 8-year follow-up study

Frailty has been linked to inflammation and changes in body composition, but the findings are inconsistent. To explore this, we used the Frailty Index (FI) definition to (1) investigate the association between levels of inflammatory markers (baseline) and change in FI score after 8 years of follow-up and (2) investigate the longitudinal associations between inflammatory markers, body composition, and frailty. Home-dwelling elderly (≥ 70 years) were invited to participate in the study and re-invited to a follow-up visit 8 years later. This study includes a total of 133 participants. The inflammatory markers included were high-sensitive C-reactive protein (hs-CRP), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), and glycoprotein acetyls (Gp-acetyls). We used the body composition markers fat mass, fat-free mass, and waist circumference. The FI score consisted of 38 variables. Additional clinical assessments such as blood pressure and body mass index (BMI), as well as information about daily medications, were collected at both visits. Linear regression model and Spearman's rank correlation were used to investigate associations. We showed that the FI score increased after 8 years, and participants with higher hs-CRP levels at baseline had the largest change in the FI score. Changes in fat mass were significantly correlated with changes in hs-CRP and IL-6, and changes in waist circumference were significantly correlated with changes in TNF-α. The use of drugs increased during the 8 years of follow-up, which may have attenuated the associations between inflammation and frailty. However, elevated concentrations of hs-CRP in the elderly may be associated with an increased risk of frailty in subsequent years.

Lipidomic perturbations of normal-weight adiposity phenotypes and their mediations on diet-adiposity associations

BACKGROUND & AIMS

Normal-weight obesity (NWO) and normal-weight central obesity (NWCO) have been linked to higher cardiometabolic risks, but their etiological bases and attributable dietary factors remain unclear. In this study we therefore aimed to identify lipidomic signatures and dietary factors related to NWO and NWCO and to explore the mediation associations of lipids in diet-adiposity associations.

METHODS

Using a high-coverage targeted lipidomic approach, we quantified 1245 serum lipids in participants with NWO (n = 150), NWCO (n = 150), or propensity-score-matched normal-weight controls (n = 150) based on the Regional Ethnic Cohort Study in Northwest China. Consumption frequency of 28 major food items was recorded using a food frequency questionnaire.

RESULTS

Profound lipidomic perturbations of NWCO relative to NWO were observed, and 249 (dominantly glycerolipids) as well as 48 (dominantly glycerophospholipids) lipids were exclusively associated with NWCO or NWO. Based on strong lipidomic signatures identified by a LASSO model, phospholipid biosynthesis was the top enriched pathway of NWCO, and sphingolipid metabolism was the top pathway of NWO. Remarkably, sphingolipids were positively associated with NWO and NWCO, but lyso-phosphatidylcholines were negatively associated with them. Rice, fruit juice, and carbonated drink intakes were positively associated with the risk of NWCO. Both global and individual lipidomic signatures, including SE(28:1_22:6) and HexCer(d18:1/20:1), mediated these diet-NWCO associations (mediation proportion: 15.92%-26.10%).

CONCLUSIONS

Differential lipidomic signatures were identified for overall and abdominal adiposity accumulation in normal-weight individuals, underlining their core mediation roles in dietary contributions to adiposity deposition.

Assessing the impact of mRNA vaccination in chronic inflammatory murine model

The implications of administration of mRNA vaccines to individuals with chronic inflammatory diseases, including myocarditis, rheumatoid arthritis (RA), and inflammatory bowel disease (IBD), are unclear. We investigated mRNA vaccine effects in a chronic inflammation mouse model implanted with an LPS pump, focusing on toxicity and immunogenicity. Under chronic inflammation, mRNA vaccines exacerbated cardiac damage and myocarditis, inducing mild heart inflammation with heightened pro-inflammatory cytokine production and inflammatory cell infiltration in the heart. Concurrently, significant muscle damage occurred, with disturbances in mitochondrial fusion and fission factors signaling impaired muscle repair. However, chronic inflammation did not adversely affect muscles at the vaccination site or humoral immune responses; nevertheless, it partially reduced the cell-mediated immune response, particularly T-cell activation. These findings underscore the importance of addressing mRNA vaccine toxicity and immunogenicity in the context of chronic inflammation, ensuring their safe and effective utilization, particularly among vulnerable populations with immune-mediated inflammatory diseases.

Association between normal-weight obesity and bone mineral density in older Korean adults: A population-based cross-sectional study

The effects of normal-weight obesity, which is defined as having a high level of body fat despite a normal body mass index, on the health of bones in older adults are poorly understood. This cross-sectional study examined the relationship between normal-weight obesity and bone mineral density in Korean adults aged 50 years or more (2815 men and 2744 women) from the 2008-2011 Korea National Health and Nutrition Examination Surveys. Between the ages of 50 and 69 years, individuals with normal-weight obesity had a higher risk of low bone mineral density (odds ratio = 1.596, 95 % confidence interval = 1.189-2.141, p = 0.002) compared with individuals with normal-weight non-obesity. However, no significant association between normal-weight obesity and bone mineral density was observed among people between the ages of 70 and 89 years. The study findings support the clinical significance of normal-weight obesity as a proxy biomarker to identify in primary care settings people who are at increased risk of developing osteoporosis at an early stage of aging.

Normal-Weight Obesity and Metabolic Syndrome in Korean Adults: A Population-Based Cross-Sectional Study

BACKGROUND

The disadvantage of using body mass index (BMI) as an obesity diagnostic tool is that it cannot distinguish between fat mass and lean mass, which may understate the impact of obesity on metabolic complications. This population-based cross-sectional study aimed to investigate the relationship between normal-weight obesity (NWO) and metabolic syndrome in Korean adults aged 20 years (5962 males and 6558 females) who took part in the Korea National Health and Nutrition Examination Surveys from 2008 to 2011.

METHODS

NWO was defined as having a BMI of 18.5 to 24.9 kg/m2 and a body fat percentage of 26.0% in males or 36.0% in females. Metabolic syndrome (MetS) was defined using the revised National Cholesterol Education Program definition, with a Korean-specific waist circumference threshold of >90 cm for males and >85 cm for females.

RESULTS

NWO males and females were 2.7 times (p < 0.001) and 1.9 times (p < 0.001) more likely to develop metabolic syndrome than normal-weight non-obese males and females, respectively. Additionally, NWO females were 1.3 times (p = 0.027) more likely to develop MetS even after adjustments for all measured covariates.

CONCLUSIONS

The current findings of the study show that NWO is a proxy biomarker of MetS to be considered for early intervention.

Leptin Concentrations Determine the Association between High-Sensitivity C-Reactive Protein Levels and Body Mass Index in Prepubertal Children

Obesity is associated with the presence of low-grade inflammation even during childhood. The dysregulation in the secretion of adipokines, such as leptin, which occurs in obesity states, could be associated with an increase in inflammatory factors already at an early age. In this cross-sectional study, we aimed to investigate the role of leptin levels in the association between body mass index (BMI) and high-sensitivity C-reactive protein (hs-CRP) in healthy schoolchildren. Leptin and hs-CRP levels were analyzed in two pediatric cohorts comprising 684 prepubertal children and 763 adolescents. hs-CRP concentrations correlated significantly with BMI and leptin levels in prepubertal males and females as well as in adolescents. However, after adjusting for leptin concentration, no significant correlation was observed between hs-CRP and BMI in prepubertal children, while the correlations remained significant in adolescents. The same differences were observed when analyzed BMI according to hs-CRP tertile after adjusting for leptin; mean BMI was not significantly different between hs-CRP tertile in prepubertal children but was significantly different in adolescents. In conclusion, the fact that leptin concentrations determine the association of BMI with hs-CRP levels in prepubertal children, but not in adolescents, suggests a role for leptin in low-grade inflammation at early ages, while other factors seem to contribute to hs-CRP levels later in life.