Susceptibility to
infections with gram-positive bacteria, which are an important trigger of exacerbations, is increased in
COPD and
asthma. Unraveling the underlying mechanisms may help developing therapeutic strategies to reduce exacerbation rates. The aim of this study was to evaluate the effects of
lipoteichoic acid (LTA), a danger signal from gram-positive bacteria, on T cell
cytokines related to
bacterial infection defense in
COPD and
asthma. T cell populations within peripheral blood mononuclear cells (PBMCs) were ex-vivo activated towards T(H)2/T(C)2 subtypes and subsequently stimulated with LTA.
IL-2 and
IL-5 concentrations in cell culture supernatants were measured by ELISA comparative between non-smokers (NS), current smokers without airflow limitation (S), smokers with moderate to severe
COPD and mild to moderate asthmatics (A) (each n=10).
IL-2 and
IL-5 baseline levels were without differences between the cohorts. After T cell activation,
IL-2 and
IL-5 releases were increased in all cohorts, however, for
IL-2 this increase was significantly higher in S and by trend in
COPD compared to the other groups. LTA time-dependently suppressed
IL-2 release in NS, S and
COPD but not in A. LTA reduced
IL-5 release in
COPD and A but not in NS and S. Summarized, LTA reduces T(H)2/T(C)2
cytokines indicating immunosuppressive effects, which are dysregulated in
COPD and
asthma. This implies a misguided response to
gram-positive bacterial infections, which might help to explain the increased susceptibility to
bacterial infections in
COPD and
asthma.