Placental Pim-1 expression is increased in obesity and regulates cytokine- and toll-like receptor-mediated inflammation

PIM1 inhibitor SMI-4a attenuated lipopolysaccharide-induced acute lung injury through suppressing macrophage inflammatory responses via modulating p65 phosphorylation

PIM kinase is involved in the cellular processes of growth, differentiation and apoptosis. However, the role of PIM1 in lipopolysaccharide (LPS)-induced acute lung injury (ALI) remains largely unknown. A trend of PIM1 in the lung tissue of LPS-induced ALI at different time points was detected. Histology, wet/dry (W/D) ratio, inflammatory cells in the bronchoalveolar lavage fluid (BALF) and survival rate analyses were performed when mice received the PIM1 inhibitor SMI-4a intratracheally 3 h before LPS administration. Cytokine production in vivo and in vitro was measured after SMI-4a pretreatment. NF-κB subunit p65 expression in nuclei and phosphorylation at Ser276 in lung tissues or cells were detected by Western blot analysis. The results showed that PIM1 mRNA and protein were upregulated in the lung tissue of LPS-induced ALI. The PIM1 inhibitor SMI-4a markedly improved the survival rate after lethal LPS administration, reduced the severity of lung edema, attenuated the histologic injuries of the lung tissue and reduced the counts of infiltrated inflammatory cells in the BALF. The PIM1 inhibitor SMI-4a suppressed the production of cytokines in LPS-treated RAW264.7 cell supernatants and BALF. Furthermore, LPS administration upregulated the levels of nuclear p65 and phosphorylated p65 (p-p65) at Ser276, whereas pretreatment with the PIM1 inhibitor SMI-4a reduced p65 upregulation in the nucleus and p-p65 at Ser276. Taken together, these data indicate that the PIM1 inhibitor SMI-4a may serve as a promising therapeutic strategy for LPS-induced ALI by suppressing macrophage production of cytokines via a reduction of p65 activities.

Placental Ras Regulates Inflammation Associated with Maternal Obesity

Heightened placental inflammation and dysfunction are commonly associated in pregnant obese women compared to their pregnant lean counterparts. The small GTPase superfamily members known as the rat sarcoma viral oncogene homolog (Ras) proteins, in particular, the K-Ras and H-Ras isoforms, have been implicated to regulate inflammation. The aims were to determine the placental Ras expression and activity with maternal obesity and its role in regulating placental inflammation. Human placenta was obtained at term Caesarean section from lean and obese pregnant women to determine the effect of maternal obesity on Ras protein expression and activity. To determine the effect of Ras on inflammation induced by bacterial endotoxin LPS and proinflammatory cytokines TNF-α or IL-1β, the chemical inhibitor lonafarnib (total Ras inhibitor) and siRNA (siKRAS and siHRAS) were used. Total Ras protein expression together with combined K-Ras and H-Ras activity was significantly increased in the placenta of obese pregnant women and when stimulated with LPS, IL-1β, or TNF-α. Lonafarnib significantly suppressed LPS-, IL-1β-, or TNF-α-induced IL-6, IL-8, MCP-1, and GRO-α expression and secretion in placental tissue. Primary trophoblast cells transfected with siKRAS or siHRAS demonstrated only K-Ras silencing significantly decreased IL-1β-, TNF-α-, or LPS-induced IL-6, IL-8, and MCP-1 expression and secretion. Furthermore, siKRAS significantly reduced downstream ERK-1/2 activation induced by LPS. In trophoblast cells, ERK-1/2 signalling is required for IL-6, IL-8, MCP-1, and GRO-α secretion. These studies implicate a role for K-Ras in regulating inflammation in human placenta. Suppressing overactive placental K-Ras function may prevent adverse fetal outcomes complicated by maternal obesity.