Metabolites and metabolic pathways associated with rheumatoid arthritis and systemic lupus erythematosus

Antioxidant and Anti-Apoptotic Neuroprotective Effects of Cinnamon in Imiquimod-Induced Lupus

BACKGROUND

Despite accumulating evidence correlating oxidative stress with lupus disease activity, the brain redox pathways are still poorly investigated. Cinnamomum cassia, a widely used spice with powerful antioxidant properties, could be a novel therapeutic candidate in lupus.

METHODS

C57BL/6J female mice were divided into five groups: sham, sham-cinnamon, lupus, lupus-cinnamon starting from induction, and lupus-cinnamon starting two weeks before induction. Lupus was induced by skin application on the right ear with 1.25 mg of 5% imiquimod cream three times per week for six weeks. Cinnamomum cassia was given orally, five days per week, at 200 mg/kg.

RESULTS

Concomitant to TLR7-MYD88 pathway activation, the p-NRF2/NRF2 and p-FOXO3/FOXO3 ratios were increased in the hippocampus and alleviated by cinnamon treatment. BCL-2 positivity was enhanced in hippocampal neurons and reversed only by preventive cinnamon administration. In vitro, exposure of hippocampal cells to the plasma of different groups induced a surge in oxidative stress. This was associated with an increased t-BID/BID ratio. Cinnamon treatment, particularly in the preventive arm, normalized these modifications.

CONCLUSIONS

Our study shows a neuroprotective effect of cinnamon by rescuing brain redox and apoptosis homeostasis in lupus, paving the way for its use as a natural therapeutic compound in the clinical management of lupus.

Exploring the relationship between oxidative stress status and inflammatory markers during primary Sjögren's syndrome: A new approach for patient monitoring

INTRODUCTION

Primary Sjögren's syndrome (pSS) is a chronic inflammatory disease primarily affects exocrine glands dysfunction. Oxidative stress (OS) is a phenomenon occurring as a result of an imbalance between the generation of free radicals and antioxidant defense system. Hence, we aimed to establish the status of OS and inflammatory response according to the pSS disease activity index. In this context, we investigated malondialdehyde (MDA), and antioxidant enzymes during pSS. The possible association between MDA and nitric oxide (NO) levels and between MDA and some pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-33).

METHODS

The study has been conducted on 53 pSS patients. The antioxidant enzymes, represented by glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD), were estimated by a colorimetric activity kit. Whereas, MDA value was assessed by measuring thiobarbituric acid reactive substances. Moreover, pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-33) and NO were respectively quantified by enzyme-linked immunosorbent assays (ELISA) and the modified Griess.

RESULTS

Interestingly, we report a notable reduction in our pSS patients' antioxidant enzyme activity, while NO, MDA and proinflammatory cytokines values were significantly increased. pSS patients with higher disease activity had much stronger increases in NO and MDA levels. No significant difference was assessed in CRP level. Additionally, substantial significant correlations between plasmatic NO and MDA levels and between MDA, NO and IL-1β, IL-6, TNF-α cytokines were reported. However, no significant association was found between NO, MDA and IL-33 concentrations.

CONCLUSION

Collectively, our data showed altered oxidant-antioxidant balance in pSS patients. MDA, NO, IL-1β, IL-6, TNF-α seem to be good indicators in monitoring disease activity. Oxidative stress was closely related to inflammation in pSS. Exploiting this relationship might provide valuable indicators in the follow-up and prognosis of pSS with a potential therapeutic value.

Metabolic profiling of urinary exosomes for systemic lupus erythematosus discrimination based on HPL-SEC/MALDI-TOF MS

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease which leads to the formation of immune complex deposits in multiple organs and has heterogeneous clinical manifestations. Currently, exosomes for liquid biopsy have been applied in diagnosis and monitoring of diseases, whereas SLE discrimination based on exosomes at the metabolic level is rarely reported. Herein, we constructed a protocol for metabolomic study of urinary exosomes from SLE patients and healthy controls (HCs) with high efficiency and throughput. Exosomes were first obtained by high-performance liquid size-exclusion chromatography (HPL-SEC), and then metabolic fingerprints of urinary exosomes were extracted by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with high throughput and high efficency. With the statistical analysis by orthogonal partial least-squares discriminant analysis (OPLS-DA) model, SLE patients were efficiently distinguished from HCs, the area under the curve (AUC) of the receiver characteristic curve (ROC) was 1.00, and the accuracy of the unsupervised clustering heatmap was 90.32%. In addition, potential biomarkers and related metabolic pathways were analyzed. This method, with the characteristics of high throughput, high efficiency, and high accuracy, will provide the broad prospect of exosome-driven precision medicine and large-scale screening in clinical applications.

Machine learning encodes urine and serum metabolic patterns for autoimmune disease discrimination, classification and metabolic dysregulation analysis

There is a wide variety of autoimmune diseases (ADs) with complex pathogenesis and their accurate diagnosis is difficult to achieve because of their vague symptoms. Metabolomics has been proven to be an efficient tool in the analysis of metabolic disorders to provide clues about the mechanism and diagnosis of diseases. Previous studies of the metabolomics analysis of ADs were not competent in their discrimination. Herein, a liquid chromatography tandem mass spectrometry (LC-MS) strategy combined with machine learning is proposed for the discrimination and classification of ADs. Urine and serum samples were collected from 267 subjects consisting of 127 healthy controls (HC) and 140 AD patients, including those with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), sicca syndrome (SS), ankylosing spondylitis (AS), systemic scleroderma (SSc) and connective tissue disease (CTD). Machine learning algorithms were encoded for the discrimination and classification of ADs with metabolomic patterns obtained by LC-MS, and satisfactory results were achieved. Notably, urine samples exhibited higher accuracy for disease differentiation and triage than serum samples. Apart from that, differential metabolites were selected and metabolite panels were evaluated to demonstrate their representativeness. Metabolic dysregulations were also investigated to gain more knowledge about the pathogenesis of ADs. This research provides a promising method for the application of metabolomics combined with machine learning in precision medicine.

Oxidative Stress Contributes to Inflammatory and Cellular Damage in Systemic Lupus Erythematosus: Cellular Markers and Molecular Mechanism

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease with complex pathogenesis, the treatment of which relies exclusively on the use of immunosuppressants. Increased oxidative stress is involved in causing inflammatory and cellular defects in the pathogenesis of SLE. Various inflammatory and cellular markers including oxidative modifications of proteins, lipids, and DNA contribute to immune system dysregulation and trigger an aggressive autoimmune attack through molecular mechanisms like enhanced NETosis, mTOR pathway activation, and imbalanced T-cell differentiation. Accordingly, the detection of inflammatory and cellular markers is important for providing an accurate assessment of the extent of oxidative stress. Oxidative stress also reduces DNA methylation, thus allowing the increased expression of affected genes. As a result, pharmacological approaches targeting oxidative stress yield promising results in treating patients with SLE. The purpose of this review is to examine the involvement of oxidative stress in the pathogenesis and management of SLE.

Serum parabens and its correlations with immunologic and cellular markers in Southern Taiwan industrialized city systemic lupus erythematosus patients

BACKGROUND

Although the immune systems of patients with systemic lupus erythematosus (SLE) are affected by both personal characteristics and environmental factors, the effects of parabens on patients with SLE have not been well studied. We investigated the indirect effects of four parabens-methylparaben (MP), ethylparaben (EP), propylparaben (n-PrP), and butylparaben (n-BuP)-on several immunological markers.

METHODS

We assessed the serum levels of MP, EP, n-PrP, and n-BuP in 25 SLE patients and correlated the concentration of each paraben with available clinical and laboratory markers, including intracellular markers of antiviral immunity and apoptosis.

RESULTS

The expression of aryl hydrocarbon receptor (AhR) was significantly negatively correlated with n-PrP levels (p = 0.03, r = -0.434). In monocytes, APO2.7 was significantly positively correlated with n-BuP levels (p = 0.019, r = 0.467). Glutathione levels were significantly negatively correlated with n-BuP levels (p = 0.019, r = -0.518). Anti- β2 glycoprotein I IgM was significantly positively correlated with both MP (p = 0.011, r = 0.585) and EP levels (p = 0.032, r = 0.506). Anti-cardiolipin IgA was significantly positively correlated with both MP (p = 0.038, r = 0.493) and n-PrP levels (p = 0.031, r = 0.508). On CD8 T cells, the early apoptotic marker annexin V was significantly negatively correlated with both MP (p < 0.05, r = -0.541) and n-BuP levels (p = 0.02, r = -0.616), and L-selectin was significantly positively correlated with both MP (p < 0.05, r = 0.47) and n-PrP levels (p = 0.02, r = 0.556).

CONCLUSION

Our findings suggest that higher parabens levels were associated with lower AhR expression in leukocytes, increased monocyte apoptosis, lower serum glutathione levels, reduced annexin V expression on CD8 T cells, and higher L-selectin levels on leukocytes.

Plasm Metabolomics Study in Pulmonary Metastatic Carcinoma

Background

The lung is one of the most common metastatic sites of malignant tumors. Early detection of pulmonary metastatic carcinoma can effectively reduce relative cancer mortality. Human metabolomics is a qualitative and quantitative study of low-molecular metabolites in the body. By studying the plasm metabolomics of patients with pulmonary metastatic carcinoma or other lung diseases, we can find the difference in plasm levels of low-molecular metabolites among them. These metabolites have the potential to become biomarkers of lung metastases.

Methods

Patients with pulmonary nodules admitted to our department from February 1, 2019, to May 31, 2019, were collected. According to the postoperative pathological results, they were divided into three groups: pulmonary metastatic carcinoma (PMC), benign pulmonary nodules (BPN), and primary lung cancer (PLC). Moreover, healthy people who underwent physical examination were enrolled as the healthy population group (HPG) during the same period. On the one hand, to study lung metastases screening in healthy people, PMC was compared with HPG. The multivariate statistical analysis method was used to find the significant low-molecular metabolites between the two groups, and their discriminating ability was verified by the ROC curve. On the other hand, from the perspective of differential diagnosis of lung metastases, three groups with different pulmonary lesions (PMC, BPN, and PLC) were compared as a whole, and then the other two groups were compared with PMC, respectively. The main low-molecular metabolites were selected, and their discriminating ability was verified.

Results

In terms of lung metastases screening for healthy people, four significant low-molecular metabolites were found by comparison of PMC and HPG. They were O-arachidonoyl ethanolamine, adrenoyl ethanolamide, tricin 7-diglucuronoside, and p-coumaroyl vitisin A. In terms of the differential diagnosis of pulmonary nodules, the significant low-molecular metabolites selected by the comparison of the three groups as a whole were anabasine, octanoylcarnitine, 2-methoxyestrone, retinol, decanoylcarnitine, calcitroic acid, glycogen, and austalide L. For the comparison of PMC and BPN, L-tyrosine, indoleacrylic acid, and lysoPC (16 : 0) were selected, while L-octanoylcarnitine, retinol, and decanoylcarnitine were selected for the comparison of PMC and PLC. Their AUCs of ROC are all greater than 0.80. It indicates that these substances have a strong ability to differentiate between pulmonary metastatic carcinoma and other pulmonary nodule lesions.

Conclusion

Through the research of plasm metabolomics, it is possible to effectively detect the changes in some low-molecular metabolites among primary lung cancer, pulmonary metastatic carcinoma, and benign pulmonary nodule patients and healthy people. These significant metabolites have the potential to be biomarkers for screening and differential diagnosis of lung metastases.

Immune, metabolism and therapeutic targets in RA (Rheumatoid Arthritis)

Rheumatoid arthritis is a classic autoimmune disease, the pathogenesis of which is closely linked to the auto-reactivity of immune cells and joint inflammation. Three cell types, namely T cells, macrophages and fibroblast-like synoviocytes (FLS), play an important role in the pathogenesis of RA. Numerous studies have pointed to a metabolic reprogramming of T cells, macrophages and FLS in the pathogenesis of RA arthritis, with alterations in different metabolic pathways of cells, mainly producing a shift from oxidative phosphorylation (OXPHOS) to glycolysis, in addition to lipid metabolism and amino acid metabolism which are also altered in the cellular activation state. Metabolic changes are regulated by metabolism-related signalling pathways, and RA is associated with two representative signalling pathways, namely the mTOR signalling pathway and the AMPK signalling pathway. In RA, both signalling pathways are activated or inhibited, and through a series of cascade reactions, different gene expressions are ultimately induced, altering intracellular metabolic pathways and promoting pro-inflammatory functions (e.g. pro-inflammatory cytokine release and FLS phenotypes), or inhibiting the expression of genes related to immune tolerance. Targeting key components of metabolic signalling pathways and key enzymes in cellular metabolic pathways in RA has emerged as a new way of finding drugs for RA, and many modulators targeting these targets have been extensively studied for their therapeutic effects in RA. In this article, we focus on cellular metabolic alterations in RA, related signalling pathways and possible drugs targeting RA metabolic pathways.