Monocytes from Metabolic Syndrome Subjects Exhibit a Proinflammatory M1 Phenotype

Gene expression profile of CD14+ blood monocytes following lifestyle-induced weight loss in individuals with metabolic syndrome

Lifestyle-induced weight loss is regarded as an efficient therapy to reverse metabolic syndrome (MetS) and to prevent disease progression. The objective of this study was to investigate whether lifestyle-induced weight loss modulates gene expression in circulating monocytes. We analyzed and compared gene expression in monocytes (CD14⁺ cells) and subcutaneous adipose tissue biopsies by unbiased mRNA profiling. Samples were obtained before and after diet-induced weight loss in well-defined male individuals in a prospective controlled clinical trial (ICTRP Trial Number: U1111-1158-3672). The BMI declined significantly (− 12.6%) in the treatment arm (N = 39) during the 6-month weight loss intervention. This was associated with a significant reduction in hsCRP (− 45.84%) and circulating CD14⁺ cells (− 21.0%). Four genes were differentially expressed (DEG’s) in CD14⁺ cells following weight loss (ZRANB1, RNF25, RB1CC1 and KMT2C). Comparative analyses of paired CD14⁺ monocytes and subcutaneous adipose tissue samples before and after weight loss did not identify common genes differentially regulated in both sample types. Lifestyle-induced weight loss is associated with specific changes in gene expression in circulating CD14⁺ monocytes, which may affect ubiquitination, histone methylation and autophagy.

Anti-inflammatory effect of β2 adrenergic stimulation on circulating monocytes with a pro-inflammatory state in high-fat diet-induced obesity

Obesity is a chronic condition associated with low-grade inflammation, and it also involves alterations of the function of the hypothalamic-pituitaryadrenal axis and the sympathetic nervous system. Adrenergic agonists such as catecholamines are important immunoregulatory molecules that are involved in modulating both metabolism and most of the mechanisms of the immune response. The first objective of this study was to determine whether the systemic inflammatory state associated with obesity is also manifested in the inflammatory profile and phenotype of circulating monocytes; and the second objective was to evaluate the effects of β2 adrenergic stimulation on the inflammatory profile and phenotype of monocytes in obesity, and whether this response could be different from that in lean individuals. C57BL/6J mice were randomly allocated to one of two diets for 18 weeks: high-fat diet in order to obtain an experimental model of obesity, and standard diet in the control lean group. Circulating monocyte expression of inflammatory cytokines (MCP-1, TNF-α, IL-8, IL-6, IL-10, and TGF-β), surface membrane marker Ly6C, inducible nitric oxide synthase and arginase-1, and Toll-like receptor 4 were evaluated through flow cytometry in the presence or absence of selective β2 adrenergic receptor agonist terbutaline. Monocytes from high-fat diet-induced obese animals presented higher expression levels of all pro-inflammatory cytokines and a higher percentage of monocytes with a pro-inflammatory phenotype than those from lean animals. β2 adrenergic stimulation induced a shift towards an anti-inflammatory activity profile and phenotype in obese mice, whereas it induced a shift towards a pro-inflammatory activity profile and phenotype in lean mice. In conclusion, β2 adrenergic stimulation in monocytes was anti-inflammatory only in obese animals, which presented a pro-inflammatory state at baseline.

Metabolic syndrome is an inflammatory disorder: A conspiracy between adipose tissue and phagocytes

Metabolic syndrome (MetS) describes a cluster of cardio-metabolic factors that predispose to type 2 diabetes mellitus (T2DM) and atherosclerotic cardiovascular disease (ASCVD). While 35% of Americans suffer from this disorder, the specific pathways related to this disease are largely underexplored. The prevailing consensus is that inflammatory pathways contribute to the pathogenesis of this disease, and therefore new research has uncovered how inflammation plays a critical role in the development and progression of MetS. The purpose of this review is to understand the role of major inflammatory mechanisms and their role in MetS. Our review identifies that adipose tissue (AT) contributes to the inflammatory pathways through the release of pro-inflammatory adipokines such as leptin and chemerin and dysregulation of anti-inflammatory adiponectin. Chemokines and cytokines deriving from monocytes are also altered and promote inflammation and insulin resistance. Circulating inflammatory biomarkers including C-reactive protein (CRP), fibrinogen, Serum amyloid A (SAA), cytokines, and chemokines have also been linked to the pathogenesis of MetS. Researchers have identified the significance of CRP levels in predicting future sequelae of MetS such as ASCVD. Mast cells in subcutaneous adipose tissue (SAT) promote both inflammation and fibrosis. Thus, both AT and phagocyte activity define MetS as an inflammatory disorder.

A longitudinal big data approach for precision health

Precision health relies on the ability to assess disease risk at an individual level, detect early preclinical conditions and initiate preventive strategies. Recent technological advances in omics and wearable monitoring enable deep molecular and physiological profiling and may provide important tools for precision health. We explored the ability of deep longitudinal profiling to make health-related discoveries, identify clinically relevant molecular pathways and affect behavior in a prospective longitudinal cohort (n = 109) enriched for risk of type 2 diabetes mellitus. The cohort underwent integrative personalized omics profiling from samples collected quarterly for up to 8 years (median, 2.8 years) using clinical measures and emerging technologies including genome, immunome, transcriptome, proteome, metabolome, microbiome and wearable monitoring. We discovered more than 67 clinically actionable health discoveries and identified multiple molecular pathways associated with metabolic, cardiovascular and oncologic pathophysiology. We developed prediction models for insulin resistance by using omics measurements, illustrating their potential to replace burdensome tests. Finally, study participation led the majority of participants to implement diet and exercise changes. Altogether, we conclude that deep longitudinal profiling can lead to actionable health discoveries and provide relevant information for precision health.

Characterization of Human Monocyte Subsets by Whole Blood Flow Cytometry Analysis

Monocytes are key contributors in various inflammatory disorders and alterations to these cells, including their subset proportions and functions, can have pathological significance. An ideal method for examining alterations to monocytes is whole blood flow cytometry as the minimal handling of samples by this method limits artifactual cell activation. However, many different approaches are taken to gate the monocyte subsets leading to inconsistent identification of the subsets between studies. Here we demonstrate a method using whole blood flow cytometry to identify and characterize human monocyte subsets (classical, intermediate, and non-classical). We outline how to prepare the blood samples for flow cytometry, gate the subsets (ensure contaminating cells have been removed), and determine monocyte subset expression of surface markers - in this example M1 and M2 markers. This protocol can be extended to other studies that require a standard gating method for assessing monocyte subset proportions and monocyte subset expression of other functional markers.

Does lipopolysaccharide-mediated inflammation have a role in OA?

The nature of the gastrointestinal microbiome determines the reservoir of lipopolysaccharide, which can migrate from the gut into the circulation, where it contributes to low-grade inflammation. Osteoarthritis (OA) is a low-grade inflammatory condition, and the elevation of levels of lipopolysaccharide in association with obesity and metabolic syndrome could contribute to OA. A 'two- hit' model of OA susceptibility and potentiation suggests that lipopolysaccharide primes the proinflammatory innate immune response via Toll-like receptor 4 and that progression to a full-blown inflammatory response and structural damage of the joint results from coexisting complementary mechanisms, such as inflammasome activation or assembly by damage-associated molecular patterns in the form of fragmented cartilage-matrix molecules. Lipopolysaccharide could be considered a major hidden risk factor that provides a unifying mechanism to explain the association between obesity, metabolic syndrome and OA.