The anti-inflammatory function of high-density lipoprotein in type II diabetes: A systematic review

BACKGROUND: Inflammation is a pathophysiological factor in diabetes and its cardiovascular complications. High-density lipoprotein (HDL) suppresses inflammation in healthy individuals. The relationship of HDL with diabetes and cardiovascular disease may be explained by HDL function rather than by HDL cholesterol level. In diabetes, HDL seems to become dysfunctional. OBJECTIVE: We performed a systematic review to answer the following research questions: Is the anti-inflammatory function of HDL diminished in individuals with diabetes and if so, what causes this? METHODS: We systematically searched Medline and Embase and included original research articles on the anti-inflammatory effects of HDL or HDL-based interventions in diabetes or diabetes models. We assessed the risk of bias of all included studies. RESULTS: Fourteen studies were included. These showed great heterogeneity in methodology, study populations, and diabetes models. Overall, HDL from subjects with type II diabetes displayed a reduced ability to suppress inflammatory processes and inflammation markers. However, the mechanisms and the in vivo effects remain largely unknown. No studies reported on HDL from individuals with other types of diabetes. In most studies, the risk of bias was high or could not be assessed. CONCLUSIONS: HDL isolated from individuals with type II diabetes showed a decreased ability to suppress inflammation. However, the direction of causality and the underlying mechanisms are unknown and should be investigated. For development of treatments directed at restoring HDL anti-inflammatory function in diabetes, a standardized method for assessing HDL anti-inflammatory function needs to be developed and in vivo biomarkers must be identified. (C) 2017 National Lipid Association. All rights reserved.