NOD2 promotes cell proliferation and inflammatory response by mediating expression of TSLP in human airway smooth muscle cells.

The newly discovered intracytosolic pattern recognition receptor nucleotide-binding oligomerization domain 2 (NOD2) has been studied as an important indicator of T helper 2 (Th2) inflammation, and its effect on regulatory T (Treg) cells is likely to modulate the immune response. In this study, we attempted to study the expression of NOD2 and its impact in human airway smooth muscle cells (HASMC). Quantitative real-time PCR (qRT-PCR) was used to measure the expression level of NOD2 in HASMC and comparisons were made between those from asthmatic and non-asthmatic donors; we found that NOD2 was significantly upregulated in asthma patient tissues and cell lines. In addition, overexpression of NOD2 apparently promotes cell proliferation and migration in HASMC. Gain-of-function in vitro experiments further showed that NOD2 overexpression significantly promotes pro-inflammatory cytokine release in HASMC. Subsequent experimental analysis indicated that thymic stromal lymphopoietin (TSLP) is involved in NOD2-mediated cellular effects in HASMC. Therefore, our results indicate that NOD2 is an asthma-related factor that can promote cell proliferation and inflammatory response by mediated expression of TSLP in HASMC. Taken together, our results indicate that NOD2 could serve as a potential diagnostic biomarker and therapeutic option for human asthma in the near future.