LDL accelerates monocyte to macrophage differentiation: Effects on adhesion and anoikis

Macrophages of genetically characterized familial hypercholesterolaemia patients show up‐regulation of LDL‐receptor‐related proteins

“…In a recent study, we have reported a significantly higher LRP5 expression in macrophages derived from CD14 + CD16 + patrolling monocytes than in those derived from pro‐inflammatory CD14 + CD16 − monocytes 67. We have also shown that a higher number of monocytes differentiate towards a CD16 + phenotype in the presence of native LDL 49. Macrophages CD16 + are usually related to a mature M2‐phenotype, also characterized for being positive for CD163 20 a scavenger receptor of the haemoglobin–haptoglobin complex involved in haeme catabolism through a process mediated by regulation of the haeme oxygenase‐1 (HMOX1) expression 79.…”

“…Indeed, FH patients carrying a null‐mutation and therefore with a long‐life exposure to high LDL levels and a severe atherogenic background were those with lower CD163 levels, both in the absence and in the presence of agLDL. In accordance, monocytes exposed to native LDL in atherogenic concentration during differentiation into macrophages also lose surface expression of CD163 49. Moreover, inverse translation studies in mice also showed a trend to lower levels Cd163 ‐PBL in diet induced mildly hypercholesterolaemic animals, and Cd163 ‐expression was highly up‐regulated in mice lacking Lrp5 , suggesting a direct relationship between high LRP5 and low CD163 levels in macrophages of FH patients.…”

“…PBMN obtained by Vacutainer CPT System were suspended in RPMI‐1640‐glutamax culture media supplemented with 10% (vol:vol) human serum (group AB blood, Lonza; Basel, Switzerland), 100 U/ml penicillin/streptomycin, 2 mM L‐glutamine, 10 mM Hepes buffer (Gibco; Thermo Fisher Scientific corporation: Waltham, MA, USA) (HS‐media) and platted on 6‐well polystyrene plates (Becton Dickenson: Franklin Lakes, NJ, USA), to obtain a cellular density of 2 ×10 6 monocyte/ml, as previously described 49. After incubation for 24 hrs, non‐adherent cells were removed by gently washing and adherent monocytes were allowed to differentiate into macrophages (MAC) for 7 days 50 changing the media every 48 hrs.…”

“…In all experiments, LDL oxidation (before and after aggregation) was excluded by assessing thiobarbituric‐acid‐reactive substances (TBARS) formation, according Ohkawa et al . 54 with slight modifications 49.…”

“…Samples were analysed in duplicates, and only mRNAs with expression levels below 32 cycles were accepted. PIK3C2A (Hs00153223_m1) and 18S‐RNA (4333760F) were used as endogenous internal controls to normalize the mRNA expression levels for human 49 and mouse samples, respectively. Data were analysed by SDS 2.4, RQ Manager 1.2.1 and DataAssits v3.0.1 software.…”