High mobility group box 1 levels are not associated with subclinical carotid atherosclerosis in patients with granulomatosis with polyangiitis but are reduced by glucocorticoids and statins

Background/Purpose: High mobility group box 1 (HMGB1) is a non-histone DNA binding protein that is passively released by dying cells or actively secreted by immunocompetent cells and the receptor for advanced glycation end-products (RAGE) is one of its receptors. Higher levels of HMGB1 have been found in patients with granulomatosis with polyangiitis (GPA) with active disease whereas higher HMGB1 and lower soluble (sRAGE) levels have been found in patients with acute atherosclerotic events suggesting sRAGE acts as a decoy receptor. This study aims to evaluate HMGB1 levels in relation to subclinical carotid atherosclerosis in GPA, and the impact of therapy on HMGB1 levels. Methods: A cross-sectional study was performed on 23 GPA patients during a quiescent phase of the disease in comparison to 20 matched controls. All study participants underwent carotid ultrasound to assess atherosclerotic plaques and intima-media thickness (IMT) and were tested for traditional risk factors for atherosclerosis, serum HMGB1 levels (ELISA-Shino Test, Kanagawa, Japan), and sRAGE levels (ELISA RD P = 0.978), HDLcholesterol (1.41 ± 0.37 vs. 1.51±0.33 mmol/L; P = 0.359), LDLcholesterol (3.01±0.79 vs. 3.29±0.82 mmol/L; P = 0.267), and a similar frequency of smoking (8.7% vs. 5.0%; P = 0.635), family history of premature coronary artery disease (CAD) (39.1% vs. 40.0%; P = 0.954), and obesity (4.3% vs. 10.0%; P = 0.446). Hypertension was only found in GPA patients (39.1% vs. 0.0%; P = 0.002) while no study participants had diabetes. Overt cardiovascular disease was found only in 13.0% of GPA patients. Statins were prescribed for 21.7% of GPA patients and 5.0% of controls (P = 0.127). Among GPA patients, prednisolone was being used by 34.8% with a median daily dose of 5.0mg (2.5-15.0) and azathioprine by 34.8%. Only two GPA patients used statins and prednisolone concomitantly. Carotid plaques were found in 30.4% of GPA patients and in 15.0% of controls (P = 0.203) and the overall IMT was similar in GPA patients and in controls (0.833±0.256 vs. 0.765±0.133mm; P = 0.861). Median serum HMGB1 levels were similar between GPA patients and controls [2.13ng/mL (1.11-7.22) vs. 2.42ng/mL (0.38-6.75); P = 0.827] as well as mean sRAGE levels (1256.1±559.6 vs. 1483.3±399.8pg/mL; P = 0.155). No correlations were found between HMGB1 and sRAGE ( = 0.068; P = 0.681) and between HMGB1 and maximum IMT in carotid arteries ( = -0.067; P = 0.720). GPA patients on prednisolone (1.77±0.76 vs. 3.53±2.06ng/ mL; P = 0.017) and statins (1.39±0.28 vs. 3.34±1.94ng/mL; P = 0.001) presented significantly lower serum HMGB1 levels whereas no difference in mean HMGB1 levels was found regarding azathioprine use (2.89±2.28 vs. 2.93±1.75; P = 0.970). Conclusion: No association was found between subclinical atherosclerosis in carotid arteries and HMGB1 levels in GPA patients. Furthermore, the use of either prednisone or statins was associated with lower HMGB1 levels in GPA patients. These findings suggest that the anti-inflammatory properties of statins include effects on serum HMGB1 levels in GPA.