Interleukin-1 receptor antagonist is associated with both lipid metabolism and inflammation in rheumatoid arthritis.
BACKGROUND
There is a relationship between cardiovascular morbidity, inflammatory activity, and changes in the lipid profile in rheumatoid arthritis (RA), although the mechanisms are not fully elaborated. Recent know-ledge that white adipose tissue (WAT) is a producer of immunologically and metabolically active substances gives another perspective to study.


OBJECTIVE
To evaluate the relationship between interleukin-1 receptor antagonist (IL-1Ra) and variables associated with WAT and inflammation in RA.


METHODS
Anthropometric, inflammatory and metabolic variables were assessed in 23 women with RA and 23 matched controls. Spearman, partial correlation and factor analyses were performed.


RESULTS
Inflammatory markers were increased in patients. In both groups, IL-1Ra correlated with leptin independent of age and BMI. IL-1Ra also correlated with haptoglobin and apolipoprotein (Apo) B in patients and with soluble TNF receptor (sTNFR) 1 in controls. In factor analysis, three latent factors were identified among patients. The first loaded on IL-1Ra, leptin, BMI, ApoB and body fat content (BF%), the second loaded on IL1-Ra and sTNF-receptors and the third showed inverse loadings on ApoA-I together with loadings on ESR, haptoglobin, orosomucoid, BF% and BMI.


CONCLUSIONS
IL-1Ra was associated with markers of inflammation and with fat-related factors in RA patients, suggesting a dualistic relationship of IL-1Ra in RA. IL-1Ra correlated independently with leptin in both patients and controls, indicating a relationship between inflammation and leptin.
Ljung
L
L
Rheumatology, Department of Public Health and Clinical Medicine, University Hospital, Umeå, Sweden.
Olsson
T
T
Engstrand
S
S
Wållberg-Jonsson
S
S
Söderberg
S
S
Rantapää-Dahlqvist
S
S
D052436:Adipose Tissue, White / Q000378:metabolism*; D001053:Apolipoproteins / Q000097:blood; D001055:Apolipoproteins B / Q000097:blood; D001172:Arthritis, Rheumatoid / Q000503:physiopathology*; D015992:Body Mass Index; D005260:Female; D006242:Haptoglobins / Q000032:analysis; D006801:Humans; D007249:Inflammation / Q000503:physiopathology*; D053590:Interleukin 1 Receptor Antagonist Protein / Q000097:blood / Q000502:physiology*; D020738:Leptin / Q000097:blood; D050356:Lipid Metabolism / Q000502:physiology; D008875:Middle Aged; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood
D001053:Apolipoproteins; D001055:Apolipoproteins B; D006242:Haptoglobins; D053590:Interleukin 1 Receptor Antagonist Protein; D020738:Leptin; D018124:Receptors, Tumor Necrosis Factor