Role of serum leptin levels and leptin receptor gene polymorphisms in systemic lupus erythematosus

Leptin gene Polymorphism and Leptin protein levels in Pediatric Autoimmune Hepatitis

BACKGROUND

Leptin plays a role in regulating energy balance, immunity, and inflammation. Studies suggest higher leptin levels might be associated with various autoimmune diseases. Most of them were in adult. To our knowledge, our study is one of the few that describe serum leptin level and leptin gene polymorphism in children with autoimmune hepatitis (AIH).

OBJECTIVE

Our study aims to explore the association between serum leptin level and genetic variations in leptin gene with the likelihood of AIH in children.

PATIENTS AND METHODS

Thirty-one children with AIH and 29 healthy children serving as a control group were included. Serum leptin levels were measured by ELISA assays. Leptin rs2167270 genotyping was done using the real time-PCR. The relationship of serum leptin level and leptin gene polymorphism with patients' data was studied. Patients follow up to assess treatment response.

RESULTS

Children with AIH had significantly higher levels of leptin compared to healthy controls. GG genotype was significantly more prevalent in the AIH group compared to controls.

CONCLUSION

High serum leptin levels and leptin gene polymorphism may play a role in AIH development. It is worthy to recognize if leptin can serve as diagnostic and/or therapeutic target in AIH in children.

Abnormal Phenylalanine Metabolism of Procapra przewalskii in Chronic Selenosis in Selenium-Enriched Habitats

Selenium (Se)-enriched habitats have led to chronic selenosis, seriously affecting the health and survival of Procapra przewalskii (P. przewalskii). Our targets were to explore the molecular mechanisms of chronic selenosis and to look for a new way to protect endangered species. The mineral contents of soils, grass, blood, and muscle were analyzed. The biochemical indices, antioxidant capability, and immune function were also investigated. The analyses of proteomics and metabolomics were also carried out. The results showed that the Se contents in the muscle and blood of P. przewalskii, and the soil and grass in the Se-enriched habitats were significantly higher than those in healthy pastures. The P. przewalskii in the Se-enriched habitats showed symptoms of anemia, decreased antioxidant capability, and low immune function. A total of 44 differential proteins and 36 differential metabolites were screened by analyzing their proteomics and metabolomics. These differential proteins and metabolites were involved in glycolysis pathway, amino acid biosynthesis, carbon metabolism, phenylalanine metabolism, and energy metabolism. In particular, phenylalanine metabolism was the common pathway of proteomics and metabolomics, which was an important finding in studying the mechanism of chronic selenosis in animals. This study will help us to further understand the mechanism of chronic selenosis in P. przewalskii, and it provides a scientific basis for the protection of endangered species in Se-enriched habitats.

Deficient leptin receptor signaling in T cells of human SLE

BACKGROUND

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease mainly mediated by IgG autoantibody. While follicular helper T (Tfh) cells are crucial for supporting IgG autoantibody generation in human SLE, underlying mechanisms for Tfh cell mal-differentiation remain unclear.

METHODS

In total, 129 SLE patients and 37 healthy donors were recruited for this study. Circulating leptin was determined by ELISA from patients with SLE and healthy individuals. CD4 T cells isolated from SLE patients and healthy donors were activated with anti-CD3/CD28 beads under cytokine-unbiased conditions in the presence or absence of recombinant leptin protein, followed by detection for Tfh cell differentiation by quantifying intracellular transcription factor Bcl-6 and cytokine IL-21. AMPK activation was assessed by analyzing phosphor-AMPK using phosflow cytometry and immunoblots. Leptin receptor expression was determined using flow cytometry and its overexpression was achieved by transfection with an expression vector. Humanized SLE chimeras were induced by injecting patients' immune cells into immune-deficient NSG mice and used for translational studies.

RESULTS

Circulating leptin was elevated in patients with SLE, inversely associated with disease activity. In healthy individuals, leptin efficiently inhibited Tfh cell differentiation through inducing AMPK activation. Meanwhile, leptin receptor deficiency was a feature of CD4 T cells in SLE patients, impairing the inhibitory effect of leptin on the differentiation of Tfh cells. As a result, we observed the coexistence of high circulating leptin and increased Tfh cell frequencies in SLE patients. Accordingly, overexpression of leptin receptor in SLE CD4 T cells abrogated Tfh cell mal-differentiation and IgG anti-dsDNA generation in humanized lupus chimeras.

CONCLUSION

Leptin receptor deficiency blocks the inhibitory effect of leptin on SLE Tfh cell differentiation, serving as a promising therapeutic target for lupus management.

High serum leptin and adiponectin levels as biomarkers of disease progression in Egyptian patients with active systemic lupus erythematosus

Objectives: Leptin and adiponectin are adipose-derived immune modulators (adipokines) that may contribute to SLE pathology and symptoms. This study aimed to evaluate the associations of serum adiponectin and leptin with clinical manifestations and disease activity in SLE patients. Methods: This is a case control study, where 70 SLE patients and 50 age- and sex-matched healthy controls were enrolled from the Rheumatology and Rehabilitation Department of Beni-Suef University Hospital from June 2020 till April 2022. The SLE disease activity index (SLEDAI) and Systemic Lupus International Collaborative clinics/America Collage of Rheumatology damage index were used to assess disease severity. Laboratory parameters including erythrocyte sedimentation rate (ESR) and serum concentrations of antinuclear antibody (ANA), anti-double stranded DNA, complement 3 and 4, lipids, and C-reactive protein (CRP) were measured and compared between SLE and control groups. Serum adiponectin and leptin were also measured by enzyme-linked immunosorbent assays (ELISA). Results: Compared to healthy controls, SLE patients exhibited significantly greater serum leptin (21.1 vs 3.9 ng/mL, p < 0.001) and adiponectin (18.1 vs 4.8 ng/mL, p < 0.001), and both values were positively correlated with SLEDAI scores (p = 0.048 and 0.042). Higher serum leptin was significantly associated with lupus nephritis (LN) (p = 0.048) as well as greater body mass index (p = 0.010), ESR (p = 0.002), serum CRP (p = 0.003), total cholesterol (p = 0.013), and uric acid (p = 0.002), while higher adiponectin was significantly associated with LN (p = 0.046). Conclusion: Serum leptin and adiponectin levels are associated with the clinical and pathological manifestations of SLE, suggesting direct involvement in disease progression and utility as diagnostic biomarkers and therapeutic targets.

Adipokines as targets in musculoskeletal immune and inflammatory diseases

Adipokines are the principal mediators in adipose signaling. Nevertheless, besides their role in energy storage, these molecules can be produced by other cells, such as immune cells or chondrocytes. Given their pleiotropic effects, research over the past few years has also focused on musculoskeletal diseases, showing that these adipokines might have relevant roles in worsening the disease or improving the treatment response. In this review, we summarize recent advances in our understanding of adipokines and their role in the most prevalent musculoskeletal immune and inflammatory disorders.

Perivascular adipose tissue in autoimmune rheumatic diseases

Perivascular adipose tissue (PVAT) resides at the outermost boundary of the vascular wall, surrounding most conduit blood vessels, except for the cerebral vessels, in humans. A growing body of evidence suggests that inflammation localized within PVAT may contribute to the pathogenesis of cardiovascular disease (CVD). Patients with autoimmune rheumatic diseases (ARDs), e.g., systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), psoriasis, etc., exhibit heightened systemic inflammation and are at increased risk for CVD. Data from clinical studies in patients with ARDs support a linkage between dysfunctional adipose tissue, and PVAT in particular, in disease pathogenesis. Here, we review the data linking PVAT to the pathogenesis of CVD in patients with ARDs, focusing on the role of novel PVAT imaging techniques in defining disease risk and responses to biological therapies.

An Update on the Role of Leptin in the Immuno-Metabolism of Cartilage

Since its discovery in 1994, leptin has been considered as an adipokine with pleiotropic effects. In this review, we summarize the actual information about the impact of this hormone on cartilage metabolism and pathology. Leptin signalling depends on the interaction with leptin receptor LEPR, being the long isoform of the receptor (LEPRb) the one with more efficient intracellular signalling. Chondrocytes express the long isoform of the leptin receptor and in these cells, leptin signalling, alone or in combination with other molecules, induces the expression of pro-inflammatory molecules and cartilage degenerative enzymes. Leptin has been shown to increase the proliferation and activation of immune cells, increasing the severity of immune degenerative cartilage diseases. Leptin expression in serum and synovial fluid are related to degenerative diseases such as osteoarthritis (OA), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Inhibition of leptin signalling showed to have protective effects in these diseases showing the key role of leptin in cartilage degeneration.