Statin-induced immunomodulation alters peripheral invariant natural killer T-cell prevalence in hyperlipidemic patients.

PURPOSE

To assess the difference in the prevalence of invariant Natural Killer T (iNKT) lymphocytes between hyperlipidemic and control individuals and to evaluate changes in iNKT cell levels after 6 months lipid lowering therapy.

METHODS

A total of 77 hyperlipidemic individuals (54 ± 5 years) were assigned to simvastatin 40 mg or ezetimibe 10 mg daily for 6 months. Fifty individuals with normal cholesterol levels were used as control. iNKT cells were measured by flow cytometry in peripheral blood.

RESULTS

Patients with hypercholesterolemia had significantly lower iNKT cell levels (percentage on the lymphocyte population) compared to control group (0.16 ± 0.04% vs 0.39 ± 0.08%, p = 0.03). iNKT cells significantly increased after 6 months treatment with simvastatin (from 0.15 ± 0.04% to 0.28 ± 0.11%, p = 0.03) but not with ezetimibe (from 0.16 ± 0.05% to 0.17 ± 0.06%, p = 0.55). Simvastatin treatment did not alter the activation status of iNKT cells as measured by HLA-DR expression. Changes of iNKT cells were independent from changes in total (r(2) = 0.009, p = 0.76) or LDL cholesterol (r(2) = 0.008, p = 0.78) reached by simvastatin.

CONCLUSIONS

Hyperlipidemic patients have reduced numbers of iNKT in peripheral circulation compared to individuals with normal cholesterol levels. Their number is increasing after long term administration of simvastatin 40 mg but not after ezetimibe.