Beyond BMI: The “Metabolically healthy obese” phenotype & its association with clinical/subclinical cardiovascular disease and all-cause mortality -- a systematic review

Background A subgroup has emerged within the obese that do not display the typical metabolic disorders associated with obesity and are hypothesized to have lower risk of complications. The purpose of this review was to analyze the literature which has examined the burden of cardiovascular disease (CVD) and all-cause mortality in the metabolically healthy obese (MHO) population. Methods Pubmed, Cochrane Library, and Web of Science were searched from their inception until December 2012. Studies were included which clearly defined the MHO group (using either insulin sensitivity and/or components of metabolic syndrome AND obesity) and its association with either all cause mortality, CVD mortality, incident CVD, and/or subclinical CVD. Results A total of 20 studies were identified; 15 cohort and 5 cross-sectional. Eight studies used the NCEP Adult Treatment Panel III definition of metabolic syndrome to define “metabolically healthy”, while another nine used insulin resistance. Seven studies assessed all-cause mortality, seven assessed CVD mortality, and nine assessed incident CVD. MHO was found to be significantly associated with all-cause mortality in two studies (30%), CVD mortality in one study (14%), and incident CVD in three studies (33%). Of the six studies which examined subclinical disease, four (67%) showed significantly higher mean common carotid artery intima media thickness (CCA-IMT), coronary artery calcium (CAC), or other subclinical CVD markers in the MHO as compared to their MHNW counterparts. Conclusions MHO is an important, emerging phenotype with a CVD risk between healthy, normal weight and unhealthy, obese individuals. Successful work towards a universally accepted definition of MHO would improve (and simplify) future studies and aid inter-study comparisons. Usefulness of a definition inclusive of insulin sensitivity and stricter criteria for metabolic syndrome components as well as the potential addition of markers of fatty liver and inflammation should be explored. Clinicians should be hesitant to reassure patients that the metabolically benign phenotype is safe, as increased risk cardiovascular disease and death have been shown.

Role of calcium in inflammation: Relevance to Alzheimer's disease

Alzheimer’s disease (AD) is neuropathologically characterized by excessive beta -amyloid (Aβ) plaques and neurofibrillary tangles composed of hyperphosphorylated tau in the brain. Although the etiology of genetic cases of AD has been attributed to mutations in presenilin and amyloid precursor protein (APP) genes, in most sporadic cases of AD, the etiology is still unknown and various predisposing factors could contribute to the pathology of AD. Predominant among these possible predisposing factors that have been implicated in AD are age, hypertension, traumatic brain injury, diabetes, chronic neuroinflammation, alteration in calcium levels and oxidative stress. Since both inflammation and altered calcium levels are implicated in the pathogenesis of AD, we wanted to study the effect of altered levels of calcium on inflammation and the subsequent effect of selective calcium channel blockers on the production of pro-inflammatory cytokines and chemokines. Our hypothesis is that Aβ, depending on it conformation, may contribute to altered levels of intracellular calcium in neurons and glial cells. We wanted to determine which conformation of Aβ was most pathogenic in terms of increasing inflammation and calcium influx and further elucidate the possibility of a link between altered calcium levels and inflammation. In addition, we wanted to test whether calcium channel blockers could inhibit the inflammation mediated by the most pathogenic form of Aβ, by antagonizing the calcium influx triggered by Aβ. Our results in human glial and neuronal cells demonstrate that the high molecular weight oligomers are the most potent at stimulating the release of pro-inflammatory cytokines IL-6 and IL-8 as well as increasing intracellular levels of calcium compared to other conformations of Aβ. Further, L-type calcium channel blockers and calmodulin kinase inhibitors are able to significantly reduce the levels of IL-6 and IL-8. These results suggest that Aβ-induced alteration of intracellular calcium levels contributes to its pro-inflammatory effect.

Factors of Inflammation in Haitian Americans and African Americans with and without Type 2 Diabetes

Chronic low-grade inflammation has been implicated in the processes leading to the development of type 2 diabetes (T2D) and its progression. Non-Hispanic Blacks bear a disproportionate burden of T2D and are highly susceptible to inflammation. This cross-sectional study assessed and compared the serum levels of established adipocytokines; interleukin-6 (IL-6), C-reactive protein (CRP), leptin, and novel adipocytokines; chemerin and omentin in Haitian and African Americans with and without T2D. The relationships of these adipocytokines with metabolic syndrome (MetS), anthropometric and HOMA2 measures by ethnicity and diabetes status were also assessed. Serum levels of IL-6, CRP, leptin, chemerin and omentin were determined by the ELISA method. HOMA2 measures were calculated for insulin sensitivity (HOMA2-IS) and insulin resistance (HOMA2-IR). Analyses of available data for 230 Haitian Americans and 241 African Americans (240 with and 231 without T2D) for the first study showed that Haitian Americans with and without MetS had lower levels of IL-6 and CRP compared to African Americans with and without MetS (P Ethnic-specific diabetes intervention and treatment programs must be designed to target Haitian Americans and African Americans as separate unique groups, in order to reduce the burden of T2D among the non-Hispanic Black community. Further research is needed to gain better understanding of the role of inflammation and T2D in this population.