Protection against Loss of Innate Defenses in Adulthood by Low Advanced Glycation End Products (AGE) Intake: Role of the Antiinflammatory AGE Receptor-1

Abstract

Increased oxidant stress and inflammation (OS/infl) are linked to both aging-related diseases and advanced glycation end products (AGEs). Whereas AGE receptor-1 (AGER1) reduces OS/infl in animals, this has not been assessed in normal humans. The objectives of the study were to determine whether AGER1 correlates with AGEs and OS/infl and a reduction of dietary AGEs (dAGEs) lowers OS/infl in healthy adults and chronic kidney disease (CKD-3) patients. This study was cross-sectional with 2-yr follow-up studies of healthy adults and CKD-3 patients, a subset of which received a reduced AGE or regular diet. The study was conducted at general community and renal clinics. Participants included 325 healthy adults (18-45 and >60 yr old) and 66 CKD-3 patients. An isocaloric low-AGE (30-50% reduction) or regular diet was given to 40 healthy subjects for 4 months and to nine CKD-3 patients for 4 wk. Relationships between age, dAGEs, serum AGEs, peripheral mononuclear cell AGE-receptors, and OS/Infl before and after reduction of dAGE intake were measured. AGEs, oxidant stress, receptor for AGE, and TNFalpha were reduced in normal and CKD-3 patients after the low-AGE diet, independently of age. AGER1 levels in CKD-3 patients on the low-AGE diet resembled 18- to 45-yr-old normal subjects. Dietary, serum, and urine AGEs correlated positively with peripheral mononuclear cell AGER1 levels in healthy participants. AGER1 was suppressed in CKD-3 subjects, whereas receptor for AGE and TNFalpha were increased. Reduction of AGEs in normal diets may lower oxidant stress/inflammation and restore levels of AGER1, an antioxidant, in healthy and aging subjects and CKD-3 patients. AGE intake has implications for health outcomes and costs and warrants further testing.