Chemokine Expression during Adipogenesis and Inflammation in Orbital Fibroblasts from Patients with Graves' Orbitopathy

The Role of Adipsin, Complement Factor D, in the Pathogenesis of Graves' Orbitopathy

Purpose

Graves' orbitopathy (GO) is an orbital manifestation of autoimmune Graves' disease, and orbital fibroblast is considered a target cell, producing pro-inflammatory cytokines and/or differentiating into adipocytes. Adipose tissue has been focused on as an endocrine and inflammatory organ secreting adipokines. We investigated the pathogenic role of a specific adipokine, adipsin, known as complement factor D in Graves' orbital fibroblasts.

Methods

The messenger RNA (mRNA) expression of multiple adipokines was investigated in adipose tissues harvested from GO and healthy subjects. Adipsin protein production was analyzed in primary cultured orbital fibroblasts under insulin growth factor (IGF)-1, CD40 ligand (CD40L) stimulation, and adipogenesis. The effect of blocking adipsin with small interfering RNA (siRNA) on pro-inflammatory cytokine production and adipogenesis was evaluated using quantitative real-time PCR, Western blot, and ELISA. Adipogenic differentiation was identified using Oil Red O staining.

Results

Adipsin gene expression was significantly elevated in GO tissue and increased after the stimulation of IGF-1 and CD40L, as well as adipocyte differentiation in GO cells. Silencing of adipsin suppressed IGF-1-induced IL-6, IL-8, COX2, ICAM-1, CCL2 gene expression, and IL-6 protein secretion. Adipsin suppression also attenuated adipocyte differentiation. Exogenous treatment of recombinant adipsin resulted in the activation of the Akt, ERK, p-38, and JNK signaling pathways.

Conclusions

Adipsin, secreted by orbital fibroblasts, may play a distinct role in the pathogenesis of GO. Inhibition of adipsin ameliorated the production of pro-inflammatory cytokines and adipogenesis in orbital fibroblasts. Our study provides an in vitro basis suggesting adipsin as a potential therapeutic target for GO treatment.

Identification of immune associated potential molecular targets in proliferative diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and causes of blindness in developed countries. Our study was designed to identify immune-related genes involved in the progression of proliferative diabetic retinopathy (PDR).

METHODS

The "GSE102485" dataset of neovascular membrane samples (NVMs) from type 1 and 2 diabetes mellitus patients was downloaded from the Gene Expression Omnibus database. Functional enrichment analyses, protein-protein interaction network (PPI) construction, and module analysis of immune pathways in NVMs and controls were conducted via Gene Set Enrichment Analysis and Metascape.

RESULTS

The significantly upregulated hallmark gene sets in DR2 and DR1 groups were involved in five immune pathways. Only CCR4, CXCR6, C3AR1, LPAR1, C5AR1, and P2RY14 were not previously reported in the context of PDR molecular pathophysiology. Except for P2RY14, all of the above were upregulated in retinal samples from experimental diabetes mouse models and human retina microvascular endothelial cells (HRMECs) treated with high glucose (HG) by quantitative Real Time Polymerase Chain Reaction (qRT-PCR).

CONCLUSION

The genes identified herein provide insight into immune-related differential gene expression during DR progression.

Serum Levels of CXCL-13, RBP-4, and IL-6, and Correlation Analysis of Patients with Graves' Disease

Objective

To investigate the serum levels of CXC chemokine 13 (CXCL-13), retinol binding protein-4 (RBP-4), and interleukin 6 (IL-6) in patients with Graves' disease (GD). The correlation between CXCL-13, RBP-4, and IL-6 levels and the basal metabolic rate (BMR) was analyzed.

Methods

118 GD patients diagnosed in our hospital were selected as the observation group from March 2017 to December 2018. According to the measured BMR value, 118 GD patients were divided into the mild group (n = 39), the moderate group (n = 47), and the severe group (n = 32), three subgroups. 60 healthy subjects were selected as the control group. The serum levels of CXCL-13, RBP-4, IL-6, TSH, FT3, and FT4 in every group were measured. Pearson correlation analysis was used to observe the correlation of serum CXCL-13, RBP-4, and IL-6 levels with TSH, FT3, FT4, and BMR.

Results

The levels of serum CXCL-13, RBP-4, and IL-6 in the observation group were higher than those of the control group, and the differences were statistically significant (P < 0.05). The levels of serum CXCL-13, RBP-4, and IL-6 in the moderate and severe groups were higher than those in the mild group, and the differences were statistically significant (P < 0.05). The levels of serum CXCL-13, RBP-4, and IL-6 in the severe group were higher than those in the moderate group, and the differences were statistically significant (P < 0.05). Pearson correlation analysis showed that the serum levels of CXCL-13, RBP-4, and IL-6 in GD patients were negatively correlated with TSH levels and positively correlated with FT3 and FT4 levels. Serum CXCL-13, RBP-4, and IL-6 levels in GD patients were positively correlated with BMR (r = 0.915, r = 0.942, r = 0.926, P < 0.001).

Conclusion

Serum CXCL-13, RBP-4, and IL-6 levels are elevated in patients with GD, and with the aggravation of the disease, the serum CXCL-13, RBP-4, and IL-6 levels also increase, showing a positive correlation, which can be used as indicators to reflect the degree of GD.