Chemerin, Resistin, and Adiponectin in Patients with Connective Tissue Diseases

Adipokines in interstitial lung diseases

Interstitial lung diseases (ILD) are a heterogenic group of respiratory diseases with complex pathogenesis. A growing number of evidence suggests role of adipose tissue and it's hormones (adipokines) in pathogenesis of various disorders, including lung tissue diseases. The aim of this study was to assess the concentrations of selected adipokines and their receptors (apelin, adiponectin, chemerin, chemerin receptor - CMKLR1) in patients with IPF (idiopathic pulmonary fibrosis) and sarcoidosis in comparison to healthy controls. We found changes in adipokines concentrations in ILD. Adiponectin concentrations were higher in all respiratory diseases patients in comparison to healthy controls. Apelin concentration in ILD patients was higher then those in healthy subjects. The trend of chemerin and CMKLR1 concentrations were similar, with highest concentrations seen in sarcoidosis. The study shows a difference of adipokines concentrations between patients with ILD and healthy controls. Adipokines are a potential marker and therapeutic target in patients with IPF and sarcoidosis.

Chemerin causes lipid metabolic imbalance and induces passive lipid accumulation in human hepatoma cell line via the receptor GPR1

AIMS

Chemerin is abundant in patients with high body mass index and metabolic syndrome possibly due to its activation in adipogenesis and glucose intolerance. It has reported that sera chemerin is positively associated with fatty liver with little known underlying mechanisms. Our aim is to study the role of chemerin in hepatic lipid metabolism.

MAIN METHODS

Oil Red O staining and TG quantitative assay were used to detect intracellular lipid accumulation. PCR, QPCR and western blot were applied to measure lipid metabolism-related genes, CMKLR1, GPR1 and inflammation marker genes. Luciferase reporter assay was employed to uncover the down-regulation of proximate promoter activities of CMKLR1 and GPR1 by SREBP1c. Antibody neutralization assay was used to address the effects of chemerin on hepatic lipid synthesis.

KEY FINDINGS

Over-expression of chemerin led to passive lipid accumulation, in human hepatoma cell line HepG2. The disable form of chemerin (chemerin 21-158) and active chemerin (chemerin 21-157) performed strongly effects on lipid metabolism in HepG2 cells. Heterologous expression of CMKLR1 or G-protein coupled receptor1 (GPR1) played similar roles in hepatocyte lipid metabolism as chemerin. Chemerin exerted its effects on lipid metabolism via GPR1 in HepG2 cells. Furthermore, free fatty acids and high concentration insulin inhibited chemerin expression. Consistently, the key lipogenic transcription factor Sterol regulatory element binding protein 1c suppressed chemerin mRNA expression and proximate promoter activities of CMKLR1 and GPR1.

SIGNIFICANCE

It implied the existence of negative feed-back regulation and further confirmed the involvement of chemerin in hepatic lipid metabolism.

Role of CCL2/CCR2 axis in the immunopathogenesis of rheumatoid arthritis: Latest evidence and therapeutic approaches

Evidence suggests that uncontrolled immune system responses and their components play a significant role in developing rheumatoid arthritis (RA), which is considered an autoimmune disease (AD). Among immune system mediators, cytokines and chemokines are involved in numerous physiological and pathological processes. CCL2 or monocyte chemoattractant protein-1 (MCP-1) is known as a CC chemokine that can induce the locomotion and recruitment of monocytes and macrophages to the site of injury. When CCL2 binds to its receptors, the most important of which is CCR2, various signaling pathways are triggered, eventually leading to various immunological events such as inflammation. This chemokine also participates in several events involved in RA pathogenesis, such as osteoclastogenesis, migration of effector T cells to the RA synovium tissue, and angiogenesis. In this review article, the role of the CCL2/CCR2 axis in RA pathogenesis and the immunotherapy opportunities based on CCL2/CCR2 axis targeting has been discussed based on existing investigations.

Altered serum level of metabolic and endothelial factors in patients with systemic sclerosis

Systemic sclerosis (SSc) is a chronic connective tissue disease characterized by progressive fibrosis, vascular impairment and immune abnormalities. In recent years, adipokines (mediators synthetized by adipose tissue) have been indicated as a possible missing link in the pathogenesis of SSc. The aim of this study was to investigate the serum concentration of metabolic adipose tissue factors: adiponectin, resistin, leptin and endothelial proteins: endothelin-1, fractalkine and galectin-3 in patients with systemic sclerosis. The study included 100 patients with confirmed SSc diagnosis and 20 healthy individuals. The concentration of respective proteins was determined by enzyme-linked immunosorbent assay. The following markers showed statistically significant increased mean concentrations in patients with SSc in comparison to healthy control: resistin (13.41 vs 8.54 ng/mL; P = 0.0012), endothelin-1 (1.99 vs 1.31 pg/mL; P = 0.0072) and fractalkine (2.93 vs 1.68 ng/mL; P = 0.0007). Elevated serum levels of galectin-3 (4.54 vs 3.26 ng/mL; P = 0.0672) and leptin (19,542 vs 14,210 pg/mL; P = 0.1817) were observed. Decreased concentration of adiponectin was found in patients with SSc (5150 vs 8847 pg/mL; P = 0.0001). Fractalkine and galectin-3 levels were significantly higher in diffuse cutaneous SSc than limited cutaneous SSc subset (3.93 ng/mL vs 2.58 ng/mL, P = 0.0018; 6.86 ng/mL vs 3.78 ng/mL, P = 0.0008, respectively) and correlated positively with modified Rodnan Skin Score in total SSc patients (r = 0.376, P = 0.0009; r = 0.236, P = 0.018, respectively). In conclusion, an increased serum level of resistin associated with increased endothelin-1 and fractalkine level and decreased adiponectin level may indicate a significant role of the adipose tissue in the development and progression of vascular abnormalities in patients with systemic sclerosis. Fractalkine and galectin-3 may participate in promoting and exacerbating the fibrotic process in SSc.