Patients with non-tuberculous mycobacterial lung disease have elevated transforming growth factor-beta following ex vivo stimulation of blood with live Mycobacterium intracellulare.

We previously found that a subset of patients with pulmonary non-tuberculous mycobacterial (pNTM) disease were taller, leaner, and had a higher prevalence of pectus excavatum and scoliosis than uninfected controls. Additionally, whole blood of pNTM patients stimulated ex vivo with live Mycobacterium intracellulare produced significantly less interferon-gamma (IFNγ) compared to that of uninfected controls. Since IFNγ production can be suppressed by transforming growth factor-beta (TGFβ), an immunosuppressive cytokine, we measured basal and M. intracellulare-stimulated blood levels of TGFβ in a group of 20 pNTM patients and 20 uninfected controls. In contrast to the IFNγ findings, we found that stimulated blood from pNTM patients produced significantly higher levels of TGFβ compared to controls. Since pNTM patients frequently possess body features that overlap with Marfan syndrome (MFS), and increased TGFβ expression is important in the pathogenesis of MFS, we posit that a yet-to-be-identified syndrome related to MFS predisposes certain individuals to develop pNTM disease.