Infection associated with elevated lipids in HAART-naive HIV-positive patients

Over a third of HIV-positive patients were infected with Chlamydia pneumoniae, which is associated with hardening of the arteries and an increased risk of heart disease, in an Italian study published in the January edition of HIV Medicine. The investigators also found that patients with lower CD4 cell counts were more likely to have Chlamydia pneumoniae and that, in patients who had never taken anti-HIV therapy, infection with Chlamydia pneumoniae was associated with elevated cholesterol and triglycerides.

Studies involving the general population have revealed that chronic Chlamydia pneumoniae infection is a cofactor involved in atherosclerosis (hardening of the arteries), and it is thought that the infection may disturb the body’s lipid metabolism. Increased lipids have been observed in HIV-positive individuals treated with HAART, and several studies have indicated an increased incidence of cardiovascular disease in HAART-treated patients. However, the role of Chlamydia pneumoniae in lipid abnormalities and cardiovascular disease in HIV-positive patients has not been evaluated. Further, it has been postulated that Chlamydia pneumoniae may interact with HIV in immune cells or in endothelial cells.

Italian investigators therefore wished to establish the prevalence of Chlamydia pneumoniae in a cohort of HIV-positive patients, its effects on the immune system and viral load, and the relationship between the infection and patients’ lipid profiles.

In 2001, blood was obtained from a random sample of 97 HIV-positive patients and PCR tested for Chlamydia pneumoniae. HIV viral load, CD3, CD4, and CD8 cell count were also measured. In addition, total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides were measured. Blood samples were obtained after an overnight fast.

The investigators also gathered demographic data, information on the duration of HIV infection, use of HAART, smoking and drinking habits, and family medical history.

Overall the prevalence of Chlamydia pneumoniae infection was 39% (39 individuals). No relationship was found between age, sex, duration of HIV infection, HIV risk group, a history of AIDS-defining illnesses, smoking and the use of cotrimoxazole and infection with Chlamydia pneumoniae.

The prevalence of the infection was 52% in patients taking HAART and 36% in patients naïve to antiretroviral therapy (difference not significant).

Investigators found that infection with Chlamydia pneumoniae was inversely related to CD4 cell count (p = 0.01). Further, amongst treatment naïve patients, viral load was significantly higher in patients positive for Chlamydia pneumoniae than it was in patients who were negative for the infection (p = 0.03).

Overall total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides were comparable between individuals who were positive and negative for Chlamydia pneumoniae. However, when the investigators restricted their analysis to the lipid profiles of patients who were naïve to antiretroviral therapy, they found that patients with Chlamydia pneumoniae had significantly higher total cholesterol (p = 0.01), LDL cholesterol (p = 0.04), and triglycerides (p = 0.05) than patients who were negative for the infection.

During the study’s follow-up period, two patients with Chlamydia pneumoniae experienced major cardiovascular disease events. No patient who was negative for the infection had an episode of cardiovascular disease.

“Our findings seem to support the hypothesis of a role for Chlamydia pneumoniae infection in the pathogenesis of lipid abnormalities in HIV-infected people”, write the investigators. They conclude that “the use of antichlamydial antibiotics might be considered, in addition to standard medication, in HIV-positive patients with coronary heart disease and chronic Chlamydia pneumoniae infection.”