Phospholipase D2 (PLD2) enzymes are expressed on the cytoplasmic
membrane of bacteria, fungi, plants, and animals and have been linked to
many critical cellular processes. Recently there are lots of research
results about PLD2 that are associated with chronic inflammation
activity of cells. To evaluate the potential influence of PLD2 on
asthma, a self-made protein including the main functional domains of
PLD2, named recombinant human phospholipase D2 (rhPLD2), was designed in
our lab. The effects of rhPLD2 on mucosal inflammation were examined by
hematoxylin and eosin staining in an ovalbumin (OVA) induced murine
model of asthma. Cytokine concentrations in BALF obtained from mice were
measured using ELISA kits. The ratio of T-bet and GATA-3 expression
level in spleen and lymph nodes after rhPLD2 administration was also
assessed through RT-PCR. It demonstrated OVA-induced mice exhibited
elevated pulmonary eosinophilia and allergic inflammation in the airways
along with increased expression of IFN-γ, IL-4 in the lung BALF. RhPLD2
could alleviate lung inflammation and reduce significantly the number of
eosinophils in peripheral blood and BALF. RhPLD2 could reverse
IFN-γ/IL-4 ratio in lymphocytes of BALF, lung, spleen, lymph nodes of
asthma mice on genetic level. Treatment of asthma mice with rhPLD2 in
vivo directly increased the frequency not only of IL-10+Treg cells, but
also of CD25+ Treg cells in peripheral blood. From a therapeutic point
of view, rhPLD2 alleviates allergic airway Inflammation via balancing
Th1/Th2 Homeostasis and increasing Treg cells and has been shown to
function in immunoregulatory activities in OVA-induced asthma mice.