Relative overexpression of macrophage-derived cytokines in orbital adipose tissue from patients with graves' ophthalmopathy

Apoptosis in orbital fibroadipose tissue and its association with clinical features in Graves' ophthalmopathy

PURPOSE

To evaluate the rate of apoptosis in orbital fibroadipose tissue in Graves' ophthalmopathy (GO) patients and investigate its associations with disease characteristics.

METHODS

Orbital tissue samples were obtained during decompression surgery from 25 GO patients. Disease activity was evaluated using the Clinical Activity Score, while the clinical features of GO were evaluated using the Total Eye Score (TES). Tissue samples of 12 patients without any thyroid or autoimmune disease were studied as controls. The rate of apoptosis was evaluated with a terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) assay, and ultrastructural features of apoptosis were evaluated with electron microscopy.

RESULTS

The rate of apoptosis in orbital fibroadipose tissue was significantly higher in GO cases than in the control group (p < 0.001) and significantly correlated with TES (r: 0.545; p = 0.005). The rate of apoptosis was 7.9% +/- 6.5%, and 22.0% +/- 7.8% in type 1 and type 2 cases, respectively (p = 0.001). The rate of apoptosis was 21.6% +/- 7.5% in eyes showing dysthyroid optic neuropathy (DON) and 6.7% +/- 5.4% in eyes without DON (p = 0.005).

CONCLUSIONS

The rate of apoptosis was high in the orbital fibroadipose tissue of GO cases and was related to the clinical features of the disease.

Susceptibility genes in Graves' ophthalmopathy: searching for a needle in a haystack?

The variety of clinical presentations of eye changes in patients with Graves' disease suggests that complex interactions between genetic, environmental, endogenous and local factors influence the development/severity of Graves' ophthalmopathy (GO). At present, the role of genetic factors in the development of GO remains unknown. Based on small case-control association studies with candidate genes, several susceptibility loci in GO have been proposed. These are human leucocyte antigen (HLA, 6p21.3), cytotoxic T-lymphocyte antigen-4 (CTLA-4, 2q33), tumour necrosis factor (TNF, 6p21.3), interferon-gamma (IFN-gamma, 12q14), intercellular adhesion molecule-1 (ICAM-1, 19p13), and thyroid stimulating hormone receptor gene (TSH-R, 14q31). Unfortunately, these results were either not confirmed or require replication in larger studies. There are many reasons for the lack of reproducibility of association studies in GO, including poor characterization of the studied groups and small sample sizes, which may result in both false positive and negative results. Thus, the genetic background of GO remains to be elucidated in future research. However, the possibility that GO may be a genetically heterogeneous disorder, or that the development of GO may be predominantly influenced by environmental factors such as cigarette smoking, can not be disregarded.

COX-2 and SCD, markers of inflammation and adipogenesis, are related to disease activity in Graves' ophthalmopathy

CONTEXT

Inflammation and adipogenesis are two parallel processes with increased activity in severe Graves' ophthalmopathy.

OBJECTIVE

The aim of this work was to define target genes for therapeutic intervention in adipogenesis and inflammation in Graves' ophthalmopathy.

DESIGN

Orbital tissue was obtained from patients with ophthalmopathy in acute or chronic phase undergoing orbital surgery to study gene expression followed by the study of potential intervention mechanisms in preadipocytes.

SETTING

Clinic of Endocrinology, University Hospital, Malmö, Sweden.

PARTICIPANTS

Patients in acute severe or in chronic phase of ophthalmopathy.

INTERVENTIONS

Lateral orbital decompression in acute phase and restorative surgery in chronic phase. In vitro treatment of preadipocytes with rosiglitazone and diclofenac.

MAIN OUTCOME MEASURE

Gene expression in intraorbital tissue or preadipocytes and differentiation of preadipocytes.

RESULTS

A marker of adipose tissue, stearoyl-coenzyme A desaturase (SCD), and the proinflammatory gene, cyclooxygenase-2 (COX-2), were overexpressed in patients in active phase compared to the chronic phase of ophthalmopathy. In growth-arrested preadipocytes stimulated with rosiglitazone, COX-2 expression increased temporarily within 1 hour and decreased to undetectable levels after 48 hours. In contrast, SCD and peroxisome proliferator-activated receptor-gamma (PPAR-gamma) expression increased continuously from day 2 to day 7 during adipogenesis. Diclofenac, an inhibitor of cyclooxygenases with antagonistic effects on PPAR-gamma, reduced the number of mature adipocytes by approximately 50%.

CONCLUSION

We conclude that inflammation and adipogenesis decrease with a decrease in activity of ophthalmopathy and that the nonsteroidal antiinflammatory drug diclofenac inhibits adipogenesis. This may represent a putative future treatment of endocrine ophthalmopathy.

Characterisation of 11beta-hydroxysteroid dehydrogenase 1 in human orbital adipose tissue: a comparison with subcutaneous and omental fat

Glucocorticoids (GCs) have a profound effect on adipose biology increasing tissue mass causing central obesity. The pre-receptor regulation of GCs by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) that activates cortisol from cortisone has been postulated as a fundamental mechanism underlying the metabolic syndrome mediating adipocyte hyperplasia and hypertrophy in the omental (OM) depot. Orbital adipose tissue (OF) is the site of intense inflammation and tissue remodelling in several orbital inflammatory disease states. In this study, we describe features of the GC metabolic pathways in normal human OF depot and compare it with subcutaneous (SC) and OM depots. Using an automated histological characterisation technique, OF adipocytes were found to be significantly smaller (parameters: area, maximum diameter and perimeter) than OM and SC adipocytes (P<0 x 001). Although immunohistochemical analyses demonstrated resident CD68+ cells in all three whole tissue adipose depots, OF CD68 mRNA and protein expression exceeded that of OM and SC (mRNA, P<0 x 05; protein, P<0 x 001). In addition, there was higher expression of glucocorticoid receptor (GR)alpha mRNA in the OF whole tissue depot (P<0 x 05). Conversely, 11beta-HSD1 mRNA together with the markers of late adipocyte differentiation (FABP4 and G3PDH) were significantly lower in OF. Primary cultures of OF preadipocytes demonstrated predominant 11beta-HSD1 oxo-reductase activity with minimal dehydrogenase activity. Orbital adipocytes are smaller, less differentiated, and express low levels of 11beta-HSD1 but abundant GRalpha compared with SC and OM. OF harbours a large CD68+ population. These characteristics define an orbital microenvironment that has the potential to respond to sight-threatening orbital inflammatory disease.

Pathogenesis of graves ophthalmopathy: implications for prediction, prevention, and treatment

PURPOSE

To review current concepts regarding the pathogenesis of Graves ophthalmopathy (GO). We have presented this information in the context of potential target sites for novel disease therapies.

DESIGN

Review of recent literature.

METHODS

Synthesis of recent literature.

RESULTS

Enlargement of the extraocular muscle bodies and expansion of the orbital fatty connective tissues is apparent in patients with GO. These changes result from abnormal hyaluronic acid accumulation and edema within these tissues and expanded volume of the orbital adipose tissues. Recent studies have suggested that the increase in orbital fat volume is caused by stimulation of adipogenesis within these tissues. The orbital fibroblast appears to be the major target cell of the autoimmune process in GO. A subset of these cells is capable of producing hyaluronic acid and differentiating into mature adipocytes, given appropriate stimulation. In addition, orbital fibroblasts from patients with GO have been shown to display immunoregulatory molecules and to express both thyrotropin receptors (TSHRs) and insulin-like growth factor 1 receptors (IGF-1Rs). Increased TSHR expression in the GO orbit appears to be the result of stimulated adipocyte differentiation. The activation of IGF-1R on orbital fibroblasts by immunoglobulins from GO patients results in increased production of both hyaluronic acid and molecules that stimulate the infiltration of activated T cells into areas of inflammation.

CONCLUSIONS

Potential targets for novel therapeutic agents to be used in GO include blocking T-cell costimulation, depleting B cells, inhibiting cytokine action, targeting the IGF-1R or the TSHR, and preventing connective tissue remodeling.

Molecular pathology of Muller's muscle in Graves' ophthalmopathy

CONTEXT

Upper lid retraction is a common sign in Graves' ophthalmopathy (GO). Whether Müller's muscle is involved in upper lid retraction has not been fully elucidated.

OBJECTIVE

The objective of the study was to understand the molecular pathology of Müller's muscle in GO.

DESIGN/SETTING/PARTICIPANTS

A method for measurement of histological changes was developed and used to correlate severity and expression of cell-specific genes in GO.

MAIN OUTCOME MEASURES

Histological changes, clinical severity of upper lid retraction, and mRNA expression in Müller's muscle in GO were measured.

RESULTS

The degree of fibrosis correlates with severity of upper lid retraction. Macrophage infiltration was increased in fibrotic areas, consistent with higher levels of macrophage-colony stimulating factor mRNA. Levels of peroxisome proliferator-activated receptor-gamma mRNA were up-regulated and correlated with fat infiltration. Decreased muscle mass correlated with lower myocardin mRNA expression. The expression of c-kit levels was decreased in diseased muscles, consistent with diminished mast cell numbers.

CONCLUSION

The pathological changes of Müller's muscle correlate with clinical severity of upper lid retraction in GO. Patterns of gene expression appear to correlate with the histopathological changes in this disease process.

Effect of high dose methylprednisolone pulse therapy followed by oral prednisolone administration on the production of anti-TSH receptor antibodies and clinical outcome in Graves' disease

Little is known about the immunosuppressive effect of glucocorticoids on TSH receptor antibodies. We observed the long-term prognosis and serum TSH binding inhibitor immunoglobulin (TBII) levels in patients with Graves' ophthalmopathy who had received intravenous methylprednisolone pulse therapy (pulse therapy) followed by oral prednisolone administration in order to ascertain how long the immunosuppressive effect of glucocorticoids continued. This is the first report on the effect of pulse therapy on Graves' disease outcome. We observed 67 patients who were treated by antithyroid drugs (ATD) alone for 2 years after pulse therapy. TBII was evaluated before and 3, 6, 12, 18, and 24 months after pulse therapy. The mean TBII decreased significantly 3 months after pulse therapy (p<0.001), and was maintained until 24 months. There were 24 patients whose TBII was positive (>15%) at 24 months, in whom the mean TBII decreased significantly 3 to 6 months after pulse therapy (p<0.001), but increased again at 12 to 24 months (p<0.05). Thus, the immunosuppressive effect of glucocorticoids may be lost at 12 months after pulse therapy in these patients. The remission rate in the pulse therapy group was 40.98%, and that of the control patient group was 48.57%. There was no significant difference between the two. These results suggest that the immunosuppressive effect of pulse therapy was temporary, and that pulse therapy did not increase remission rate of Graves' disease.

Role of macrophage tissue infiltration in metabolic diseases

PURPOSE OF REVIEW

White adipose tissue is necessary for optimal energy homeostasis and the excessive development of fat mass is clearly associated with the metabolic syndrome. The fact that adipocytes secrete a number of specific factors or 'adipokines' has forced a reassessment of the involvement of adipose tissue in a wide range of physiological and pathophysiological processes. Obesity has recently been described as a 'low-grade' inflammatory condition, a state proposed to represent a common determinator in the genesis of obesity-associated pathologies, i.e. diabetes and atherosclerosis.

RECENT FINDINGS

Recent reports of an increase in the number of macrophages that infiltrate the fat mass in obese individuals led to the suggestion that adipose tissue itself is a source and site of inflammation.

SUMMARY

This review summarizes recent data on the characterization of the macrophage population in fat tissue. Their origin, fate and activation will be considered. The potential involvement of adipose tissue macrophages in the development of insulin resistance and vascular pathologies, as well as in the control of adipose tissue growth and metabolism, will be examined.

Association of tumor necrosis factor and human leukocyte antigen DRB1 alleles with Graves' ophthalmopathy

Tumor necrosis factor (TNF)-alpha plays a central role in the development of ophthalmopathy in patients with Graves' disease (GD). The aim of this study was to investigate the association of TNF promoter polymorphisms at positions -1031 (T-1031C), -863 (C-863A), -857 (C-857T), -308 (G-308A), and -238 (G-238A) with Graves' ophthalmopathy (GO). We studied the distribution of TNF and human leukocyte antigen (HLA) DRB1 alleles in 228 Polish white patients with GD, 106 of whom had ophthalmopathy (NOSPECS class > or = III) and 248 healthy subjects. TNF -308A and HLA-DRB1*03 alleles were significantly increased in patients with GD compared with healthy subjects. Stratification analysis revealed no independent association of -308A with GD when the DRB1*03 status was considered. Subdividing GD according to eye involvement revealed that the distribution of TNF promoter haplotypes differed significantly in patients with or without ophthalmopathy. The haplotype containing the -238A allele was absent in GO. The association of G-238A with GO was independent of DRB1 alleles. These results indicate that TNF G-308A is associated with susceptibility to GD (however, this association is not independent of HLA-DRB1*03) and that TNF G-238A is associated with the development of ophthalmopathy, suggesting that G-238A or a gene in linkage disequilibrium may be disease modifying in GD.