The term “meta-inflammation” refers to chronic metabolic inflammation,
which is thought to have an important role in the pathogenesis of numerous metabolic
diseases. Majority of authors agree that inflammation, as a component of immune
system, may serve as a link between obesity and numerous diseases. Hence, the role
of meta-inflammation in the pathogenesis of obesity-related diseases is extensively
investigated. Mitochondrial dysfunction in adipocytes is lately regarded as a primary
cause of adipose tissue inflammation. This newly proposed hypothesis contradicts
currently prevailing concept that “adipose tissue hypoxia” underlies adipose tissue
dysfunction in obesity. Infiltration of adipose tissue by immune cells is one of the
hallmarks of adipose tissue dysfunction. Based on the current knowledge, adipose
tissue (AT) macrophages are considered to have a pivotal role in the development of
adipose tissue inflammation and dysfunction. Macrophages that infiltrate the adipose
tissue are divided into: pro-inflammatory (M1) and anti-inflammatory (M2) AT
macrophages. Studies have shown that M1 AT macrophages contribute to insulin
resistance by producing pro-inflammatory cytokines. Conversely, M2 AT macrophages
are involved in the repair or remodeling of tissues. In obesity, adipose tissue becomes
inflamed and goes through cellular remodeling. Adipocytes increase in number
(hyperplasia) and size (hypertrophy), become infiltrated by macrophages and undergo
fibrosis. Hypertrophic adipocytes secrete more pro-inflammatory molecules that lead to
a shift of M2 to M1 AT macrophages. Adipose tissue dysfunction in obesity is
characterized by changes on cellular and molecular level, which include immune cells
such as T cells, B cells and dendritic cells. However, their role in meta-inflammation
and adipose tissue dysfunction remains to be fully elucidated. Novel findings suggest
that dysregulation of autophagy in adipose tissue has an important role in metainflammation.
Studies have shown that there is a strong relationship between
the prenatal and perinatal environment and obesity-related diseases. Childhood
obesity is associated with meta-inflammation that affects not only adipose tissue but
other organs as well. Since adipose tissue dysfunction in obesity plays a pivotal role in
disturbing homeostatic processes in the human body, it is of essential importance that
health care systems at the global level work on implementation of precautionary
strategies in order to prevent the development and progression of meta-inflammation
and obesity-related metabolic complications starting at early stages of life.
Keywords: Adipose tissue dysfunction, Adipose tissue dendritic cells, Antiinflammatory
cytokines, Autophagy, B cells, Macrophages, Macrophage
polarization, Meta-inflammation, Obesity, Pro-inflammatory cytokines, T
regulatory cells.
