Relationship of plasma interleukin-18 concentrations to traditional and non-traditional cardiovascular risk factors in patients with systemic lupus erythematosus, Rheumatology, Volume 45, Number 9, September 2006, Pages 1148-1153, T. Tso, W.N. Huang, H.Y. Huang, et. al.

Some of the same problems that can occur in blood vessels in patients with diabetes may also be at work in lupus patients, increasing their risk for heart disease and strokes through the activity of a small inflammatory protein called interleukin-18.

Lupus patients have an increased risk for hardening of the arteries (or atherosclerosis), which leads to heart disease and strokes. There are probably many factors at work, including antiphospholipid antibodies, increased levels of homocysteine, high blood fats (known as triglycerides), stiffness in blood vessel walls, and a pre-diabetes syndrome called insulin resistance which can come on in anyone, but can be related to weight gain and steroid use (which is a problem for many lupus patients).

Less well-studied are inflammatory disorders in the bloodstream that may contribute to those risks. In this study, researchers in Taiwan undertook to look at a small inflammatory protein called interleukin-18 (IL18) that circulates in the blood, and to see whether it is associated with risk factors for heart disease in lupus patients.

Recent reports have suggested that IL-18 can be elevated in lupus. In addition, some other research has found a link between high levels of IL-18 and a number of risk factors for heart disease in the population at large. This same link has been observed in patients with diabetes, but no previous studies have looked for this connection in lupus patients.

Blood samples were donated by 72 Chinese women with lupus and 40 women without lupus. The lupus patients had significantly higher levels of IL-18 than healthy women in the same age ranges. The researchers found that high levels of IL-18 were associated with higher levels of insulin resistance to the actions of insulin, which are early signs of diabetes. High IL-18 was also associated with other risk factors for heart disease, including high levels of homocysteine, and increased stiffness of blood vessels in the lupus patients.

The researchers believe that it is possible that all these risk factors are working together to cause the increased IL-18 to appear in the blood. If so, that raises the intriguing possibility that drugs developed to treat diabetes might be used to help prevent heart disease in lupus patients.