Nogo-A reduces ceramide de novo biosynthesis to protect from heart failure.

AIMS: Growing evidence correlate the accrual of the sphingolipid ceramide in plasma and cardiac tissue with heart failure (HF). Regulation of sphingolipid metabolism in the heart and the pathological impact of its derangement remain poorly understood. Recently, we discovered that Nogo-B, a membrane protein of endoplasmic reticulum, abundant in the vascular wall, down-regulates the sphingolipid de novo biosynthesis via serine palmitoyltransferase (SPT), first and rate liming enzyme, to impact vascular functions and blood pressure. Nogo-A, a splice isoform of Nogo, is transiently expressed in cardiomyocyte (CM) following pressure overload. Cardiac Nogo is up-regulated in dilated and ischaemic cardiomyopathies in animals and humans. However, its biological function in the heart remains unknown. METHODS AND RESULTS: We discovered that Nogo-A is a negative regulator of SPT activity and refrains ceramide de novo biosynthesis in CM exposed to haemodynamic stress, hence limiting ceramide accrual. At 7 days following transverse aortic constriction (TAC), SPT activity was significantly up-regulated in CM lacking Nogo-A and correlated with ceramide accrual, particularly very long-chain ceramides, which are the most abundant in CM, resulting in the suppression of 'beneficial' autophagy. At 3 months post-TAC, mice lacking Nogo-A in CM showed worse pathological cardiac hypertrophy and dysfunction, with ca. 50% mortality rate. CONCLUSION: Mechanistically, Nogo-A refrains ceramides from accrual, therefore preserves the 'beneficial' autophagy, mitochondrial function, and metabolic gene expression, limiting the progression to HF under sustained stress.

Mammalian Target of Rapamycin Pathway Assessment in Antiphospholipid Antibody-Positive Patients with Livedo.

OBJECTIVE: In antiphospholipid antibody (aPL) nephropathy, activation of the mammalian target of rapamycin (mTOR) contributes to endothelial cell proliferation, a key finding of aPL microvascular disease. Here, we examined mTOR activation in the skin of aPL-positive patients with livedo. METHODS: Three patient groups with livedo were studied: (1) persistently aPL-positive with systemic lupus erythematosus (SLE); (2) persistently aPL-positive without SLE; and (3) aPL-negative SLE (control). After collecting aPL-related medical history, two 5-mm skin biopsies of livedo were performed on each patient: (1) peripheral (erythematous-violaceous lesion); and (2) central (nonviolaceous area). We stained specimens for phosphorylated protein kinase B (p-AKT) and phosphorylated S6 ribosomal protein (p-S6RP) as mTOR activity markers, CD31 to identify endothelial cells, and Ki-67 to show cellular proliferation. We counted cells in the epidermis and compared mTOR-positive cell counts between peripheral and central samples, and between patient groups, using Freidman test and Wilcoxon signed-rank test. RESULTS: Ten patients with livedo reticularis were enrolled: 4 aPL-positive without SLE (antiphospholipid syndrome [APS] classification met, n = 3), 4 aPL-positive SLE (APS classification met, n = 3), and 2 aPL-negative SLE (control). In all aPL-positive patients, epidermal p-AKT and p-S6RP staining were significantly increased in both peripheral and central skin samples when compared to aPL-negative SLE controls; both were more pronounced in the lower basal layers of epidermis. CONCLUSION: Our study demonstrates increased mTOR activity in livedoid lesions of aPL-positive patients with or without SLE compared to aPL-negative patients with SLE, with more prominent activity in the lower basal layers of the epidermis. These findings may serve as a basis for further investigating the mTOR pathway in aPL-positive patients.

Lymphatic Function in Autoimmune Diseases.

Lymphatic vessels are critical for clearing fluid and inflammatory cells from inflamed tissues and also have roles in immune tolerance. Given the functional association of the lymphatics with the immune system, lymphatic dysfunction may contribute to the pathophysiology of rheumatic autoimmune diseases. Here we review the current understanding of the role of lymphatics in the autoimmune diseases rheumatoid arthritis, scleroderma, lupus, and dermatomyositis and consider the possibility that manual therapies such as massage and acupuncture may be useful in improving lymphatic function in autoimmune diseases.

Design and Syntheses of Highly Potent Teixobactin Analogues against Staphylococcus aureus, Methicillin-Resistant Staphylococcus aureus (MRSA), and Vancomycin-Resistant Enterococci (VRE) in Vitro and in Vivo.

The cyclic depsipeptide, teixobactin, kills a number of Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), and Mycobacterium tuberculosis without detectable resistance. To date, teixobactin is the only molecule in its class that has shown in vivo antibacterial efficacy. In this work, we designed and synthesized 10 new in vivo ready teixobactin analogues. These analogues showed highly potent antibacterial activities against Staphylococcus aureus, MRSA, and vancomycin-resistant enterococci (VRE) in vitro. One analogue, d-Arg4-Leu10-teixobactin, 2, was found to be noncytotoxic in vitro and in vivo. Moreover, topical instillation of peptide 2 in a mouse model of S. aureus keratitis decreased the bacterial bioburden (>99.0% reduction) and corneal edema significantly as compared to untreated mouse corneas. Collectively, our results have established the high therapeutic potential of a teixobactin analogue in attenuating bacterial infections and associated severities in vivo.

Highly Efficient Supramolecular Aggregation-Induced Emission-Active Pseudorotaxane Luminogen for Functional Bioimaging.

The direct tracking of cells using fluorescent dyes is a constant challenge in cell therapy due to aggregation-induced quenching (ACQ) effect and biocompatibility issues. Here, we demonstrate the development of a biocompatible and highly efficient aggregation-induced emission (AIE)-active pseudorotaxane luminogen based on tetraphenylethene conjugated poly(ethylene glycol) (TPE-PEG2) (guest) and α-cyclodextrin (α-CD) (host). It is capable of showing significant fluorescent emission enhancement at the 400-600 nm range when excited at 388 nm, without increasing the concentration of AIE compound. The fluorescent intensity of TPE-PEG2 solution was effectively enhanced by 4-12 times with gradual addition of 1-4 mM of α-CD. 2D NOSEY 1H NMR revealed clear correlation spots between the characteristic peaks of α-CD and PEG, indicating the interaction between protons of ethylene glycol and cyclodextrin, and the structures are mainly based on threaded α-CD. The host-guest complex exhibits boosted fluorescent emission because the PEG side chains are confined in "nano-cavities" (host), thus, applying additional restriction on intermolecular rotation of TPE segments. In vitro cell experiments demonstrated the potential of AIE-active pseudorotaxane polymer as a biocompatible bioimaging probe.

LFA-1/ICAM-1 Ligation in Human T Cells Promotes Th1 Polarization through a GSK3ß Signaling-Dependent Notch Pathway.

In this study, we report that the integrin LFA-1 cross-linking with its ligand ICAM-1 in human PBMCs or CD4(+) T cells promotes Th1 polarization by upregulating IFN-γ secretion and T-bet expression. LFA-1 stimulation in PBMCs, CD4(+) T cells, or the T cell line HuT78 activates the Notch pathway by nuclear translocation of cleaved Notch1 intracellular domain (NICD) and upregulation of target molecules Hey1 and Hes1. Blocking LFA-1 by a neutralizing Ab or specific inhibition of Notch1 by a γ-secretase inhibitor substantially inhibits LFA-1/ICAM-1-mediated activation of Notch signaling. We further demonstrate that the Notch pathway activation is dependent on LFA-1/ICAM-1-induced inactivation of glycogen synthase kinase 3ß (GSK3ß), which is mediated via Akt and ERK. Furthermore, in silico analysis in combination with coimmunoprecipitation assays show an interaction between NICD and GSK3ß. Thus, there exists a molecular cross-talk between LFA-1 and Notch1 through the Akt/ERK-GSK3ß signaling axis that ultimately enhances T cell differentiation toward Th1. Although clinical use of LFA-1 antagonists is limited by toxicity related to immunosuppression, these findings support the concept that Notch inhibitors could be attractive for prevention or treatment of Th1-related immunologic disorders and have implications at the level of local inflammatory responses.