Behind the High Pneumonia Risk in Lupus: Innate Defect?

Sep 18, 2014

Confirming the high pneumonia risk in lupus patients, researchers in Spain have found that it may precede the onset of the immune disorder. Their biological studies suggest that a particular underlying immune abnormality may explain both.

Rúa-Figueroa I, Nóvoa J, García-Laorden MI, et al.Clinical and Immunogenetic Factors Associated with Pneumonia in Patients with Systemic Lupus Erythematosus: A Case-Control Study. Journal of Rheumatology  (2014)  41:1801-1807.

In patients with systemic lupus erythematosus (SLE), the incidence of pneumonia is significantly higher than in the general population regardless of immunosuppressive therapy. The risk is especially increased in patients with severe SLE and in those with the one genetic variant of FCGR2A, a gene previously associated with susceptibility to bacteremic pneumococcal pneumonia, according to the authors of a new case-control study.

The researchers compared genetic profiles in 232 SLE patients, including 36 who had experienced at least one episode of pneumonia and 196 age- and sex-matched controls with no episodes of pneumonia.

The researchers found that this genetic variant of FCGR2A appears to predispose patients with SLE to pneumonia, and that the risk is even higher in female patients ages 15-39. In addition, it was also found that the increased risk of pneumonia may actually precede the diagnosis of SLE, suggesting that certain genetic factors might predispose to both infection and SLE.

“This finding might make sense from a biologic point of view," the authors state, because the presence of this allele reduces the ability of immunoglobulin G to bind to C-reactive protein (CRP), which plays a key role in the innate immune system by making capsulated bacteria, particularly S. pneumonia, more susceptible to phagocytosis.

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