Lipid Alterations in Systemic Sclerosis

The differential crosstalk of the skin-gut microbiome axis as a new emerging actor in systemic sclerosis

OBJECTIVES

We characterized the microbiota in SSc, focusing on the skin-oral-gut axis and the serum and faecal free fatty acid (FFA) profile.

METHODS

Twenty-five SSc patients with ACA or anti-Scl70 autoantibodies were enrolled. The microbiota of faecal, saliva and superficial epidermal samples was assessed through next-generation sequencing analysis. GC-MS was used to quantify faecal and serum FFAs. Gastrointestinal symptoms were investigated with the University of California Los Angeles Scleroderma Clinical Trial Consortium Gastrointestinal Tract Instrument (UCLA GIT-2.0) questionnaire.

RESULTS

The ACA+ and anti-Scl70+ groups displayed different cutaneous and faecal microbiota profiles. The classes of cutaneous Sphingobacteriia and Alphaproteobacteria, the faecal phylum Lentisphaerae, the levels of the classes Lentisphaeria and Opitutae, and the genus NA-Acidaminococcaceae were significantly higher in faecal samples from the ACA+ patients than in samples from the anti-Scl70+ patients. The cutaneous Sphingobacteria and the faecal Lentisphaerae were significantly correlated (rho = 0.42; P = 0.03). A significant increase in faecal propionic acid was observed in ACA+ patients. Moreover, all levels of faecal medium-chain FFAs and hexanoic acids were significantly higher in the ACA+ group than in the anti-Scl70+ group (P < 0.05 and P < 0.001, respectively). In the ACA+ group, the analysis of the serum FFA levels showed an increasing trend in valeric acid.

CONCLUSION

Different microbiota signatures and FFA profiles were found for the two groups of patients. Despite being in different body districts, the cutaneous Sphingobacteria and faecal Lentisphaerae appear interdependent.

Association Between Lipid Profile and Risk of Incident Systemic Sclerosis: A Nationwide Population-Based Study

Background and Aims

Lipid metabolism is altered in systemic sclerosis (SSc), mediating activation of immune cells and fibroblasts. However, it is unclear whether altered lipid profile is associated with a risk of developing SSc. We aimed to assess the association between lipid profile and risk of incident SSc.

Methods

From a Korean nationwide database, individuals without SSc who underwent national health check-ups in 2009 were selected and followed-up through 2019. Serum levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride were measured on the health check-up date in 2009. Individuals who developed SSc during follow-up were identified. Multivariable Cox models were performed to estimate the risk of incident SSc according to TC, HDL-C, LDL-C, and triglyceride levels, respectively.

Results

Of the 9,894,996 individuals selected, 1355 individuals developed SSc during a mean follow-up of 9.2 years (incidence rate=1.49 per 100,000 person-years). Levels of TC (adjusted hazard ratio [aHR] 0.959, 95% confidence interval [CI] 0.945-0.974), HDL-C (aHR 0.968, 95% CI 0.950-0.987), LDL-C (aHR 0.968, 95% CI 0.952-0.983) were inversely associated with the risk of incident SSc, whereas no significant association was observed between levels of triglyceride (aHR 1.004, 95% CI 0.998-1.011) and risk of incident SSc.

Conclusion

Serum levels of TC, HDL-C, and LDL-C were inversely associated with the risk of incident SSc. Our findings provide new insights that altered lipid profile could be considered a non-causal biomarker associated with incident SSc, which could help early diagnosis. The underlying mechanism for this association needs further studies.

Whole Blood and Plasma-Based Lipid Profiling Reveals Distinctive Metabolic Changes in Systemic Lupus Erythematosus and Systemic Sclerosis

Autoimmune diseases (AID), such as systemic lupus erythematosus (SLE) and systemic sclerosis (SS), are complex conditions involving immune system dysregulation. Diagnosis is challenging, requiring biomarkers for improved detection and prediction of relapses. Lipids have emerged as potential biomarkers due to their role in inflammation and immune response. This study uses an untargeted C18 RP-LC-MS lipidomics approach to comprehensively assess changes in lipid profiles in patients with SLE and SS. By analyzing whole blood and plasma, the study aims to simplify the lipidomic analysis, explore cellular-level lipids, and compare lipid signatures of SLE and SS with healthy controls. Our findings showed variations in the lipid profile of SLE and SS. Sphingomyelin and ceramide molecular species showed significant increases in plasma samples from SS patients, suggesting an atherosclerotic profile and potentially serving as lipid biomarkers. Phosphatidylserine species in whole blood from SLE patients exhibited elevated levels supporting previously reported dysregulated processes of cell death and defective clearance of dying cells in this AID. Moreover, decreased phospholipids bearing PUFA were observed, potentially attributed to the degradation of these species through lipid peroxidation processes. Further studies are needed to better understand the role of lipids in the pathological mechanisms underlying SLE and SS.

Malondialdehyde Serum Levels in Patients with Systemic Sclerosis Relate to Dyslipidemia and Low Ventricular Ejection Fraction

Systemic sclerosis (SSc) is a chronic disease characterized by vasculopathy with the involvement of dysfunctional microcirculatory vessels. Features of the disease include progressive fibrosis of the skin and internal organs and systemic inflammation characterized by the presence of circulating autoantibodies and proinflammatory cytokines. Furthermore, macrovascular disease and atherosclerosis are more common in patients with SSc than in the general population. Oxidative stress plays a crucial role in the development of several processes, including endothelial dysfunction, cancer, inflammation, and atherogenesis. Malondialdehyde (MDA) is a well-established marker of oxidative stress. In this work, we have analyzed the relationship between serum MDA levels and clinical, laboratory, and vascular characteristics in a well-characterized cohort of 53 patients with SSc. A multivariable analysis was performed to study the relationship between circulating MDA and disease characteristics in patients with SSc. Cardiovascular assessment was also performed, including ultrasonography of the carotid and aorta, and echocardiography. MDA showed a significant and positive relationship with the serum levels of lipid profile molecules such as total cholesterol (β coefficient = 0.006 (95% CI: 0.0004 to 0.01), nmol/mL, p = 0.037) and LDL cholesterol (β coefficient = 0.008 (95% CI: 0.001 to 0.01) nmol/mL, p = 0.017). On the contrary, most manifestations of the disease, including skin, lung, and joint involvement, as well as the presence of digital ulcers, were not related to MDA. However, high MDA levels were significantly and independently associated with lower ventricular ejection fraction after adjustment for covariates (β coefficient = -0.04 (95% CI: -0.06 to -0.02), nmol/mL, p = 0.001). In conclusion, serum MDA levels were related to higher levels of total and LDL cholesterol and a lower left ventricular ejection fraction in patients with SSc. MDA could serve as a potential biomarker of dyslipidemia and heart failure in SSc.

Ceramides in Autoimmune Rheumatic Diseases: Existing Evidence and Therapeutic Considerations for Diet as an Anticeramide Treatment

Autoimmune rheumatic diseases (AIRDs) constitute a set of connective tissue disorders and dysfunctions with akin clinical manifestations and autoantibody responses. AIRD treatment is based on a comprehensive approach, with the primary aim being achieving and attaining disease remission, through the control of inflammation. AIRD therapies have a low target specificity, and this usually propels metabolic disturbances, dyslipidemias and increased cardiovascular risk. Ceramides are implicated in inflammation through several different pathways, many of which sometimes intersect. They serve as signaling molecules for apoptosis, altering immune response and driving endothelial dysfunction and as regulators in the production of other molecules, including sphingosine 1-phosphate (S1P) and ceramide 1-phosphate (C1P). With lipid metabolism being severely altered in AIRD pathology, several studies show that the concentration and variety of ceramides in human tissues is altered in patients with rheumatic diseases compared to controls. As a result, many in vitro and some in vivo (animal) studies research the potential use of ceramides as therapeutic targets in rheumatoid arthritis (RA), ankylosing spondylitis, systemic lupus erythematosus, fibromyalgia syndrome, primary Sjögren's syndrome, systemic sclerosis, myositis, systemic vasculitis and psoriatic arthritis. Furthermore, the majority of ceramide synthesis is diet-centric and, as a result, dietary interventions may alter ceramide concentrations in the blood and affect health. Subsequently, more recently several clinical trials evaluated the possibility of distinct dietary patterns and nutrients to act as anti-ceramide regimes in humans. With nutrition being an important component of AIRD-related complications, the present review details the evidence regarding ceramide levels in patients with AIRDs, the results of anti-ceramide treatments and discusses the possibility of using medical nutritional therapy as a complementary anti-ceramide treatment in rheumatic disease.