Hypoxia potentiates tumor necrosis factor-α induced expression of inducible nitric oxide synthase and cyclooxygenase-2 in white and brown adipocytes.

Obesity involves hypoxic adipose tissue and low-grade chronic inflammation. We investigated the impact of hypoxia on inflammatory response to TNF-α in white and brown adipocytes. In response to TNF-α, the expression of the inducible enzymes iNOS and COX-2 was prominently and selectively potentiated during hypoxia while only moderately under normoxia. Levels of their products, nitrite and prostaglandinE2 were elevated accordingly. NS398, a selective COX-2 inhibitor, reduced nitrite levels. The expression of PGC-1α, a transcriptional co-activator involved in mitochondrial biogenesis, and PPARγ, a transcription factor involved in adipocyte homeostasis, was reduced by TNF-α during hypoxia. These results suggest that hypoxia potentiates the inflammatory response by TNF-α in both white and brown adipocytes and downregulates the transcription factors involved in adipocyte function.

SAXS imaging reveals optimized osseointegration properties of bioengineered oriented 3D-PLGA/aCaP scaffolds in a critical size bone defect model.

Healing large bone defects remains challenging in orthopedic surgery and is often associated with poor outcomes and complications. A major issue with bioengineered constructs is achieving a continuous interface between host bone and graft to enhance biological processes and mechanical stability. In this study, we have developed a new bioengineering strategy to produce oriented biocompatible 3D PLGA/aCaP nanocomposites with enhanced osseointegration. Decellularized scaffolds -containing only extracellular matrix- or scaffolds seeded with adipose-derived mesenchymal stromal cells were tested in a mouse model for critical size bone defects. In parallel to micro-CT analysis, SAXS tensor tomography and 2D scanning SAXS were employed to determine the 3D arrangement and nanostructure within the critical-sized bone. Both newly developed scaffold types, seeded with cells or decellularized, showed high osseointegration, higher bone quality, increased alignment of collagen fibers and optimal alignment and size of hydroxyapatite minerals.

Inhibition of activated ERK1/2 and JNKs improves vascular function in mouse aortae in the absence of nitric oxide.

Activation of mitogen-activated protein kinases (MAPKs) is important for vascular contraction. Decreased nitric oxide availability combined with activation of MAPKs contributes to an increase in vascular tone. In this study, we have determined the involvement of extracellular signal-regulated kinases1/2 (ERK1/2) and c-Jun N-terminal kinases (JNKs) in reactivity of mouse aortae in the absence of nitric oxide. Additionally, we have examined the contribution of these kinases to endothelium-dependent and prostaglandin F(2α) (PGF(2α))-induced contractions. Precontracted aortic rings were treated with MAPK/ERK kinase1/2 (MEK1/2) inhibitor U0126 or JNKs inhibitor SP600125 to determine reactivity after inhibition of nitric oxide synthase using organ bath chambers. Additionally, rings were pretreated with or without these inhibitors to assess PGF(2α)- and acetylcholine-induced, endothelium-dependent contractions. Specificity of the inhibitors was evaluated in each aortic ring by determining the phosphorylation levels of ERK1/2 and c-Jun using Bio-Plex™ phospho-protein detection kit. In the absence of nitric oxide both inhibitors caused relaxation, and the dilator response was increased by 2.5-fold using SP600125 in comparison with U0126. Transient endothelium-dependent contractions were blocked by U0126, whereas SP600125 strongly attenuated sustained PGF(2α)-induced contractions. U0126 inhibited only phosphorylation of ERK1/2, while SP600125 at higher concentrations not only inhibited phosphorylation of c-Jun but also ERK1/2 phosphorylation. In conclusion, the present study demonstrates that in aortae inhibition of activated ERK1/2 and JNKs mediates vascular relaxation, even in the absence of nitric oxide. Activation of ERK1/2 contributes predominantly to transient endothelium-dependent contractions while JNKs, possibly synergistically with ERK1/2, leads to sustained PGF(2α)-induced contractions.