Wang-Dong Xu, Yu-Jing Zhang, Hai-Feng Pan, Dong-Qing Ye*

Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, 81 Meishan Road, Hefei, Anhui, 230032, PR China;

*Correspondence: Dong-Qing Ye, M.D, Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, 81 Meishan Road, Hefei, Anhui, 230032, PR China,

E-mail: ydq@ahmu.edu.cn; Tel.: +86 551 5167726; Fax: +86 551 5161171.

Dear editor,

McMahon, et al1 have reported that high plasma leptin levels confer increased risk of atherosclerosis in systemic lupus erythematosus (SLE) patients, and are associated with inflammatory oxidised lipids. In the study, leptin levels are significantly higher in patients than in controls, which are also higher in the 43 SLE patients with plaque than without plaque and associate with inflammatory biomarkers of atherosclerosis such as piHDL (proinflammatory high-density lipoprotein), Lp(a) and OxPL/apoB100, furthermore, age and hypertension, and so on.

In fact, relationship between leptin and SLE have been studied increasingly both in humans and animal models, but different results exist2-10. Hahn, et al4 developed a mouse model of multigenic lupus exposed to environmental factors known to accelerate atherosclerosis in humans--high-fat diet with or without injections of the leptin, where the lupus-prone strain (BWF1 mice), addition of leptin increased proinflammatory high-density lipoprotein scores, indicating the presence of piHDL as well as atherosclerosis, accelerated proteinuria. Moreover, several investigations have confirmed the higher leptin levles are significantly associated with SLE compared to controls6,8,10, especially the serum leptin levels with age, hypertension3,5,8,9, but Chung, et al5 found no significant relationship between leptin or adiponection levels and coronary calcification in SLE pantients and controls. On contrary, lower leptin levels in SLE patients4 or no statistically significant differences between leptin levels in SLE patients and the controls7 are discovered as well.

As is known, leptin belongs to the type I cytokine superfamily and has an important role in regulating immune functions. Leptin protects T lymphocytes from apoptosis and regulates T-cell proliferation and activation, and influences cytokine production from T lymphocytes, generally switching the phenotype toward a Th1 response 11-13. Consequently, in order to better understand the link between SLE, atherosclerosis and leptin, further to clarify the associaiton of leptin and SLE based on large samples not only in humans, but in animals are still needed.

References

1. McMahon M, Skaggs BJ, Sahakian L, et al. High plasma leptin levels confer increased risk of atherosclerosis in women with systemic lupus erythematosus, and are associated with inflammatory oxidised lipids. Ann Rheum Dis 2011;70:1619-24.

2. Hahn BH, Lourenco EV, McMahon M, et al. Pro-inflammatory high- density lipoproteins and atherosclerosis are induced in lupus-prone mice by a high-fat diet and leptin. Lupus 2010;19:913-7.

3. Kim HA, Choi GS, Jeon JY, et al. Leptin and ghrelin in Korean systemic lupus erythematosus. Lupus 2010;19:170-4.

4. De Sanctis JB, Zabaleta M, Bianco NE, et al. Serum adipokine levels in patients with systemic lupus erythematosus. Autoimmunity 2009;42:272-4.

5. Chung CP, Long AG, Solus JF, et al. Adipocytokines in systemic lupus erythematosus: relationship to inflammation, insulin resistance and coronary atherosclerosis. Lupus 2009;18:799-806.

6. Vadacca M, Margiotta D, Rigon A, et al. Adipokines and systemic lupus erythematosus: relationship with metabolic syndrome and cardiovascular disease risk factors. J Rheumatol 2009;36:295-7.

7. Wisowska M, Rok M, StepieK, et al. Serum leptin in systemic lupus erythematosus. Rheumatol Int 2008;28:467-73.

8. Ryan MJ, McLemore GR Jr, Hendrix ST. Insulin resistance and obesity in a mouse model of systemic lupus erythematosus. Hypertension 2006;48:988-93.

9. Sada KE, Yamasaki Y, Maruyama M, et al. Altered levels of adipocytokines in association with insulin resistance in patients with systemic lupus erythematosus. J Rheumatol 2006;33:1545-52.

10. Garcia-Gonzalez A, Gonzalez-Lopez L, Valera-Gonzalez IC, et al. Serum leptin levels in women with systemic lupus erythematosus. Rheumatol Int 2002;22:138-41.

11. Fantuzzi G. Adipose tissue, adipokines, and inflammation. J Allergy Clin Immunol 2005;115:911-9.

12. Zhang Y, Proenca R, Maffei M, et al. Positional cloning of the mouse obese gene and its human homologue. Nature 1994;372:425-32.

13. Busso N, So A, Chobaz-Peclat V, et al. Leptin signaling deficiency impairs humoral and cellular immune responses and attenuates experimental arthritis. J Immunol 2002;168:875-82.

Conflict of Interest:

None declared