Novel role of NPY in neuroimmune interaction and lung growth after intrauterine growth restriction

Abstract

Individuals with intrauterine growth restriction (IUGR) are at risk for chronic lung disease. Using a rat model, we showed in our previous studies that altered lung structure is related to IL-6/STAT3 signaling. As neuropeptide Y (NPY), a coneurotransmitter of the sympathetic nervous system, regulates proliferation and immune response, we hypothesized that dysregulated NPY after IUGR is linked to IL-6, impaired myofibroblast function, and alveolar growth. IUGR was induced in rats by isocaloric low-protein diet; lungs were analyzed on embryonic day (E) 21, postnatal day (P) 3, P12, and P23. Finally, primary neonatal lung myofibroblasts (pnF) and murine embryonic fibroblasts (MEF) were used to assess proliferation, apoptosis, migration, and IL-6 expression. At E21, NPY and IL-6 expression was decreased, and AKT/PKC and STAT3/AMPKα signaling was reduced. Early reduction of NPY/IL-6 was associated with increased chord length in lungs after IUGR at P3, indicating reduced alveolar formation. At P23, however, IUGR rats exhibited a catch-up of body weight and alveolar growth coupled with more proliferating myofibroblasts. These structural findings after IUGR were linked to activated NPY/PKC, IL-6/AMPKα signaling. Complementary, IUGR-pnF showed increased survival, impaired migration, and reduced IL-6 compared with control-pnF (Co-pnF). In contrast, NPY induced proliferation, migration, and increased IL-6 synthesis in fibroblasts. Additionally, NPY mice showed reduced IL-6 signaling and less proliferation of lung fibroblasts. Our study presents a novel role of NPY during alveolarization: NPY regulates ) IL-6 and lung STAT3/AMPKα signaling, and) proliferation and migration of myofibroblasts. These new insights in pulmonary neuroimmune interaction offer potential strategies to enable lung growth.

Novel functional role of GH/IGF-I in neonatal lung myofibroblasts and in rat lung growth after intrauterine growth restriction

“…Prior studies of our group showed reduced alveolar growth after IUGR followed by pulmonary catchup growth, perturbed matrix remodeling in adult rats, and dysfunction of lung fibroblast (4,6,7,66). Our previous findings coupled with the functional role of GH/IGF-I in fibrotic processes let us hypothesize that dysregulation of the pulmonary intrinsic GH/IGF-I signaling is linked to myofibroblast function and lung growth after IUGR with catchup growth.…”

“…Adult Wistar rats were obtained from Charles River (Sulzfeld, Germany), housed in a humidity-and temperature-controlled room at 22 Ϯ 2°C, and exposed to a 12-h:12-h dark-light cycle. IUGR and postnatal catchup growth were induced as described previously (7,66). Briefly, time-mated rats received an isocaloric low-protein diet (8.0% casein, No.…”

“…Immunofluorescence staining. Localization of GH receptor (GH-R) and IGF-IR was analyzed by immunofluorescent staining, as described previously (66). Sections were incubated with the relevant primary antibody: polyclonal rabbit anti-GH-R (AB78426; 1:200; Abcam), polyclonal rabbit anti-IGF-IR (No.…”

“…Cell culture studies. Primary neonatal lung myofibroblasts (pnF) were isolated at P3 from rats after IUGR (pnF IUGR ) and control (pnF Co ) using a one-step incubation procedure, as previously described (66). Primary neonatal lung myofibroblasts were cultured in DMEM medium (No.…”

“…For example, elastin synthesis (25,41) and increased deposition of collagen coupled with perturbed protease activity are structural features in lungs of former IUGR rats (7). Moreover, recent studies from our group demonstrated that IUGR inhibits alveolar formation early after birth; on the contrary, rapid postnatal weight gain after IUGR enables alveolar catchup in rats and activates myofibroblasts (66). The molecular mechanisms by which myofibroblasts and lung growth after IUGR are directed remain unclear.…”