Uncontrolled activation of tumor necrosis factor receptor-associated factor (TRAF) proteins may result in profound tissue injury by linking surface signals to cytokine release. Here we show that a ubiquitin E3 ligase component, Fbxo3, potently stimulates cytokine secretion from human inflammatory cells by destabilizing a sentinel TRAF inhibitor, Fbxl2. Fbxo3 and TRAF protein in circulation positively correlated with cytokine responses in septic subjects and we furthermore identified a hypofunctional Fbxo3 human polymorphism. A small molecule inhibitor targeting Fbxo3 was sufficient to lessen severity of cytokine-driven inflammation in several murine disease models. These studies identify a pathway of innate immunity that may characterize subjects with altered immune responses during critical illness or provide a basis for therapeutic intervention targeting TRAF protein abundance.

Taken together, the decreased expression of cytokine and chemokine receptors in aged B-MSCs compromises their protective role by perturbing the potential of B-MSCs to become activated and mobilize to the site of injury.

The enzyme acyl-CoA:lysophosphatidylcholine acyltransferase (Lpcat1) is a critical cytosolic enzyme needed for lung surfactant synthesis that catalyzes an acyltransferase reaction by adding a palmitate to the sn-2 position of lysophospholipids. Here we report that histone H4 protein is subject to palmitoylation catalyzed by Lpcat1 in a calcium-regulated manner. The enzyme acyl-CoA:lysophosphatidylcholine acyltransferase (Lpcat1) was recently cloned from lung epithelia and is indispensable for generation of pulmonary surfactant. Lpcat1 catalyzes an O-acyltransferase reaction by covalently adding saturated acyl-CoAs (palmitoyl groups, 16:0) to its acceptor lysophospholipids. Specifically, in the lung, it catalyzes an oxyester linkage between palmitate and lysophosphatidylcholine to generate dipalmitoylphosphatidylcholine, the major surface tension-lowering component of pulmonary surfactant in the remodeling pathway (1, 2). However, Lpcat1 appears to be somewhat promiscuous and acts on substrates that include lysophosphatidylcholine, lysoplasmanylcholine, and lysophosphatidylglycercol (1-3). Notably, in addition to lipid substrates, O-acyltransferases can also lipidate some protein substrates (4 -7). These enzymes share a highly conserved histidine residue within a catalytic core that is essential for their functionality.Protein palmitoylation, a prototypical form of lipidation, is an important post-translational modification that occurs ubiquitously in eukaryotes. Protein palmitoylation is generally categorized as S-palmitoylation, N-palmitoylation, and O-palmitoylation based on the chemical linkage between donor and acceptor substrates. Among these, S-palmitoylation is best characterized and involves generation of a reversible thioester bond between a cysteine residue and a palmitate group (8). As many as 250 proteins were found to be modified by S-palmitoylation in mammalian neurons, and these reactions are largely catalyzed by aspartate-histidine-histidine-cysteine (DHHC) palmitoyl acyltransferase family members (8, 9). The biochemistry of N-palmitoylation and O-palmitoylation, however, is less studied. One known substrate for N-palmitoylation is the Sonic Hedgehog protein because its NH 2 -terminal cysteine is palmitoylated via an amide linkage by Hedgehog acyltransferase (Hhat) (5). O-Palmitoylation is exemplified by Wnt/Wg proteins that harbor an oxyester linkage between monounsaturated palmitate and a serine residue. Another recently described O-palmitoylation target, the peptide hormone preghrelin, is modified by octanoylation at a serine residue. The enzymes that catalyze the oxyester linkages within Wnt/Wg proteins and preghrelin are porcupine (6) and ghrelin O-acyltransferase (7), respectively. The physiological consequences of palmitoylation are diverse; by increasing substrate hydrophobicity, these lipidation reactions appear to modulate interactions of substrates with other biomolecules, often affecting signal transduction, protein stability, intracellular trafficking, and localization (10 -12).Histo...

Acute respiratory distress syndrome (ARDS) is an important cause of morbidity and mortality, with no currently effective therapies. Several preclinical studies have shown that human mesenchymal stem cells (hMSCs) have therapeutic potential for patients with ARDS because of their immunomodulatory properties. The clinical use of hMSCs has some limitations, such as the extensive manipulation required to isolate the cells from bone marrow aspirates and the heterogeneity in their anti-inflammatory effect in animal models and clinical trials. The objective of this study was to improve the protective anti-inflammatory capacity of hMSCs by evaluating the consequences of preactivating hMSCs before use in a murine model of ARDS. We injected endotoxemic mice with minimally manipulated hMSCs isolated from the bone marrow of vertebral bodies with or without prior activation with serum from ARDS patients. Minimally manipulated hMSCs were more efficient at reducing lung inflammation compared with isolated and in vitro expanded hMSCs obtained from bone marrow aspirates. Where the most important effect was observed was with the activated hMSCs, independent of their source, which resulted in increased expression of interleukin (IL)-10 and IL-1 receptor antagonist (RN), which was associated with enhancement of their protective capacity by reduction of the lung injury score, development of pulmonary edema, and accumulation of bronchoalveolar lavage inflammatory cells and cytokines compared with nonactivated cells. This study demonstrates that a low manipulation during hMSC isolation and expansion increases, together with preactivation prior to the therapeutic use of hMSCs, would ensure an appropriate immunomodulatory phenotype of the hMSCs, reducing the heterogeneity in their anti-inflammatory effect. STEM CELLS TRANSLATIONAL MEDICINE 2013;2:884 -895

Background:The contribution of long-chain acyl-CoA dehydrogenase (LCAD) to human fatty acid oxidation is not understood. Results: LCAD localizes to lung alveolar type II cells, which produce pulmonary surfactant; LCAD-deficient mice have surfactant dysfunction. Conclusion: LCAD is important for lung energy metabolism and lung function. Significance: LCAD may play a role in human lung disease and unexplained sudden infant death.