Resolution-Associated Lactoferrin Peptides Limit LPS Signaling and Cytokine Secretion from Human Macrophages.

The neutrophil granule protein lactoferrin is cleaved and accumulates in efferocytic macrophages as inflammation is resolved. Two peptides present within a resolution-associated 17 kDa fragment of lactoferrin promote the termination of inflammation in vivo by enhancing murine macrophage reprogramming. Here, we report that these two bioactive tripeptides, phenylalanine-lysine-aspartic acid and phenylalanine-lysine-glutamic acid (FKD and FKE, respectively), inhibit ERK and cJun activation following human macrophage exposure to LPS. In addition, these peptides at low concentrations (1-10 µM) modulate human macrophage reprogramming to an anti-inflammatory/pro-resolving phenotype. This was reflected by inhibition of LPS-induced TNF-α and IL-6 secretion and increased IL-10 levels. Moreover, we found naturally occurring FKE analogs (FKECH and FKECHLA) can recapitulate the activity of the short peptide in regulating macrophage cytokine secretion, whereas a reversed EKF peptide was inert in this respect. Curiously, FKD and FKE also regulated cytokine production by bone marrow-derived mouse macrophages, but in a very different fashion than their effect on human macrophages. Thus, lactoferrin peptides limit pro-inflammatory signaling and cytokine production by LPS-activated human macrophages and thereby enhance the resolution of inflammation.

Novel non-invasive early detection of lung cancer using liquid immunobiopsy metabolic activity profiles.

Lung cancer is the leading cause of cancer death worldwide. Survival is largely dependent on the stage of diagnosis: the localized disease has a 5-year survival greater than 55%, whereas, for spread tumors, this rate is only 4%. Therefore, the early detection of lung cancer is key for improving prognosis. In this study, we present an innovative, non-invasive, cancer detection approach based on measurements of the metabolic activity profiles of immune system cells. For each Liquid ImmunoBiopsy test, a 384 multi-well plate is loaded with freshly separated PBMCs, and each well contains 1 of the 16 selected stimulants in several increasing concentrations. The extracellular acidity is measured in both air-open and hermetically-sealed states, using a commercial fluorescence plate reader, for approximately 1.5 h. Both states enable the measurement of real-time accumulation of 'soluble' versus 'volatile' metabolic products, thereby differentiating between oxidative phosphorylation and aerobic glycolysis. The metabolic activity profiles are analyzed for cancer diagnosis by machine-learning tools. We present a diagnostic accuracy study, using a multivariable prediction model to differentiate between lung cancer and control blood samples. The model was developed and tested using a cohort of 200 subjects (100 lung cancer and 100 control subjects), yielding 91% sensitivity and 80% specificity in a 20-fold cross-validation. Our results clearly indicate that the proposed clinical model is suitable for non-invasive early lung cancer diagnosis, and is indifferent to lung cancer stage and histological type.

How Similar Are Proteins and Origami?

Protein folding and structural biology are highly active disciplines that combine basic research in various fields, including biology, chemistry, physics, and computer science, with practical applications in biomedicine and nanotechnology. However, there are still gaps in the understanding of the detailed mechanisms of protein folding, and protein structure-function relations. In an effort to bridge these gaps, this paper studies the equivalence of proteins and origami. Research on proteins and origami provides strong evidence to support the use of origami folding principles and mechanical models to explain aspects of proteins formation and function. Although not identical, the equivalence of origami and proteins emerges in: (i) the folding processes, (ii) the shape and structure of proteins and origami models, and (iii) the intrinsic mechanical properties of the folded structures/models, which allows them to synchronically fold/unfold and effectively distribute forces to the whole structure. As a result, origami can contribute to the understanding of various key protein-related mechanisms and support the design of de novo proteins and nanomaterials.

Macrophages, meta-inflammation, and immuno-metabolism.

Current research depicts specific modes of immunity and energy metabolism as being interrelated at the molecular, cellular, organ and organism level. Hence, whereas M2 (alternatively-activated) macrophages dominate insulin-sensitive adipose tissue in the lean, M1-skewed (classically-activated) macrophages accumulate in parallel to adiposity in the obese, and promote inflammation and insulin resistance, that is, meta-inflammation. The latest frontier of immuno-metabolism explores the coregulation of energy metabolism and immune function within hematopoietic cells. M1-skewed macrophages are sustained in edematous, hypoxic tissues by anaerobic glycolysis, whereas mitochondrial biogenesis and respiration dominates in M2 cells. We review the underlying mechanisms and the consequences of the transition from M2 to M1 predominance in adipose tissue, as well as the extracellular signals and transcription factors that control macrophage phenotypes and impose distinct metabolic modes.

Approach for comparing protein structures and origami models.

The research fields of proteins and origami have intersected in the study of folding and de-novo design of proteins. However, there is limited knowledge on the analogy between protein structures and origami models. We propose a general approach for comparing protein structures with origami models, and present a test case, comparing transmembrane ß-barrel and α-helical barrel with the Yoshimura and Kresling origami models. While both shapes and structures may look similar, we demonstrated that the ß-barrel and the α-helical barrel are in agreement only with the shape and structural characteristics of the Kresling model. Through the analogy, it is explained how the structural characteristic can help the ß-barrel and α-helical barrel to adjust length and diameter in response to changes in the membrane structure. However, such conformations only apply to the α-helical barrel, and the ß-barrel, in spite of resembles to the Kresling model, remains stiff due to hydrogen bonds between the ß-strands. Thus, our analysis suggests that there are similar patterns between protein structures and origami models and that the proposed approach may provide important insight on the role that the structure of a protein fulfils, and on the preferred structural design of novel proteins with unique characteristics.

A 17-kDa Fragment of Lactoferrin Associates With the Termination of Inflammation and Peptides Within Promote Resolution.

During the resolution of inflammation, macrophages engulf apoptotic polymorphonuclear cells (PMN) and can accumulate large numbers of their corpses. Here, we report that resolution phase macrophages acquire the neutrophil-derived glycoprotein lactoferrin (Lf) and fragments thereof in vivo and ex vivo. During the onset and resolving phases of inflammation in murine peritonitis and bovine mastitis, Lf fragments of 15 and 17 kDa occurred in various body fluids, and the murine fragmentation, accumulation, and release were mediated initially by neutrophils and later by efferocytic macrophages. The 17-kDa fragment contained two bioactive tripeptides, FKD and FKE that promoted resolution phase macrophage conversion to a pro-resolving phenotype. This resulted in a reduction in peritoneal macrophage numbers and an increase in the CD11blow subset of these cells. Moreover, FKE, but not FKD, peptides enhanced efferocytosis of apoptotic PMN, reduced TNFα and interleukin (IL)-6, and increased IL-10 secretion by lipopolysaccharide-stimulated macrophages ex vivo. In addition, FKE promoted neutrophil-mediated resolution at high concentrations (100 µM) by enhancing the formation of cytokine-scavenging aggregated NETs (tophi) at a low cellular density. Thus, PMN Lf is processed, acquired, and "recycled" by neutrophils and macrophages during inflammation resolution to generate fragments and peptides with paramount pro-resolving activities.