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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.

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 upregulated in dilated and ischemic cardiomyopathies in animals and humans. However, its biological function in the heart remains unknown.We discovered that Nogo-A is a negative regulator of SPT activity and refrains ceramide de novo biosynthesis in CM exposed to hemodynamic stress, hence limiting ceramide accrual. At 7 days following transverse aortic constriction (TAC), SPT activity was significantly upregulated 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 50% mortality rate. 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.

Photosensitivity in lupus and subsequent systemic disease flares contribute to disease burden and is incompletely understood. Skin communicates with lymphoid tissues via lymphatics and reduced lymphatic flow in murine models results in skin inflammation and autoimmunity. Here, we demonstrate that the skin of lupus patients and multiple murine lupus models are characterized by lymphatic flow dysfunction. Improving lymphatic flow in murine lupus models via manual lymphatic drainage or by utilizing a transgenic model with increased lymphatics ameliorated cutaneous photosensitivity and diminished draining lymph node germinal center B cell and plasmablast responses. Improved lymphatic flow limited B cell responses via acting on a stromal-immune circuit previously described by our lab. Increased lymphatic flow increases stromal CCL2, which modulates monocyte function and limits B cell responses. This work provides a link between cutaneous photosensitivity and systemic disease in lupus and suggests that improving lymphatic flow or targeting the lymph node microenvironment could be potential therapeutic targets.

ObjectiveIn 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.MethodsThree 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.ResultsTen 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.ConclusionOur 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 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.

The integrin LFA-1 plays a key role in T-cell motility, which is critical for host defense and is also main driver of autoimmune diseases. However, whether and how LFA-1 signalling can modulate T-cell effector functions remain to be understood. We performed gene expression analysis of LFA-1-stimulated human T-cells and identified genomic signatures associated with Notch and TGF-β pathways, both involved in T-cell differentiation. The activation of Notch pathway in motile T-cells was confirmed by the nuclear translocation of cleaved Notch intracellular domain and up-regulation of target genes Hey1 and Hes1. LFA-1 stimulation of naïve peripheral blood mononuclear cells was found to promote T-cell Th1 polarization through a GSK3β signalling-dependent Notch pathway. We further detected that LFA-1 signalling up-regulated Stat3 and/or JNK activation-dependent expression of Smad7, Smurf2 and Ski causing T-cell TGF-β unresponsiveness. LFA-1-stimulated naïve T-cells were refractory to TGF-β-mediated induction of Foxp3+ iTreg or RORγt+ Th17 differentiation. Of note, peripheral or splenic T-cells isolated from patients with rheumatoid arthritis, type1 diabetes or thyroiditis showed constitutively high expression of Tbet. Pretreatment of cells with blocking anti-LFA-1 antibody, specific inhibitors or siRNA against identified molecules restored LFA-1-mediated modulation of T-cell functional phenotypes. Thus, LFA-1-mediated signalling is crucial for T-cell immunoregulation concurrent with T-cell motility, involving both Notch and TGF-β pathways. These findings have implications for normal immunologic functions and also have therapeutic relevance for inflammatory diseases.