Insulin-like growth factor 1 signaling in the placenta requires endothelial nitric oxide synthase to support trophoblast function and normal fetal growth.

Currently, there is no effective treatment for placental dysfunction in utero. In a ligated mouse model of fetal growth restriction (FGR), nanoparticle-mediated human insulin-like 1 growth factor (hIGF1) gene delivery (NP-Plac1-hIGF1) increased hIGF1 expression and maintained fetal growth. However, whether it can restore fetal growth remains to be determined. Using the endothelial nitric oxide synthase knockout (eNOS-/-) mouse model, a genetic model of FGR, we found that despite inducing expression of hIGF1 in the placentas treated with NP-Plac1-hIGF1 (P = 0.0425), FGR did not resolve. This was associated with no change to the number of fetal capillaries in the placental labyrinth; an outcome which was increased with NP-Plac1-hIGF1 treatment in the ligated mouse model, despite increased expression of angiopoietin 1 (P = 0.05), and suggested IGF1 signaling in the placenta requires eNOS to modulate placenta angiogenesis. To further assess this hypothesis, BeWo choriocarcinoma cell line and human placental explant cultures were treated with NP-Plac1-hIGF1, oxidative stress was induced with hydrogen peroxide (H2O2), and NOS activity was inhibited using the inhibitor NG-monomethyl-l-arginine (l-NMMA). In both BeWo cells and explants, the protective effect of NP-Plac1-hIGF1 treatment against H2O2-induced cell death/lactate dehydrogenase release was prevented by eNOS inhibition (P = 0.003 and P < 0.0001, respectively). This was associated with an increase in mRNA expression of oxidative stress markers hypoxia inducing factor 1α (HIF1α; P < 0.0001) and ADAM10 (P = 0.0002) in the NP-Plac1-hIGF1 + H2O2 + l-NMMA-treated BeWo cells. These findings show for the first time the requirement of eNOS/NOS in IGF1 signaling in placenta cells that may have implications for placental angiogenesis and fetal growth.

The role of FIBCD1 in response to Aspergillus fumigatus in lung epithelial cells.

Chitin, a polysaccharide, is ubiquitously found in nature and has been known to be an active immunogen in mammals, and interacts with Toll-like, mannose and glucan receptors, to induce cytokine and chemokine secretions. FIBCD1 is a tetrameric type II transmembrane endocytic vertebrate receptor that binds chitin, is found in human lung epithelium and modulates lung epithelial inflammatory responses to A. fumigatus cell wall polysaccharides. We previously reported the detrimental role of FIBCD1 in a murine model of pulmonary invasive aspergillosis. However, the effect that chitin and chitin-containing A. fumigatus conidia exerts on lung epithelium following exposure through FIBCD1 is not yet fully explored. Using both in vitro and in vivo strategies, we examined how lung and lung epithelial gene expression are modified after exposure to fungal conidia or chitin fragments in the presence or absence of FIBCD1. FIBCD1 expression was associated with a decrease in inflammatory cytokines with increasing size of chitin (dimer-oligomer). Thus, our results demonstrate that FIBCD1 expression modulates cytokine and chemokine expression in response to A. fumigatus conidia that is modified by the presence of chitin particles.

FIBCD1 Deficiency Decreases Disease Severity in a Murine Model of Invasive Pulmonary Aspergillosis.

Aspergillus fumigatus is a ubiquitous mold associated with the development of pulmonary diseases that include invasive pulmonary aspergillosis (IPA), an often fatal opportunistic infection. FIBCD1 is a transmembrane endocytic membrane receptor widely expressed on human epithelium. Although FIBCD1 was previously shown to bind chitin, modulate fungal colonization of the gut, and inhibit intestinal inflammation, the role of FIBCD1 in the context of lung fungal infection remains unknown. In this study, we observed that mortality, fungal burden, and tissue histopathology were decreased in the absence of FIBCD1 in murine IPA. Quantitative RT-PCR analyses demonstrated decreased inflammatory cytokines in the lungs of neutrophil-depleted FIBCD1-/- mice with IPA, when compared with wild-type controls. In contrast, inflammatory cytokines were increased in immune-competent FIBCD1-/- mice after fungal aspiration, suggesting that the presence of neutrophils is associated with cytokine modulation. In contrast to the clear IPA phenotype, FIBCD1-/- mice with systemic infection or bleomycin-induced lung injury exhibited similar morbidity and mortality when compared with their wild-type counterparts. Thus, our study identifies a detrimental role of FIBCD1 in IPA.