Inflammatory adipokines contribute to insulin resistance in active acromegaly and respond differently to different treatment modalities

BACKGROUND

Active acromegaly is associated with insulin resistance, but it is uncertain whether inflammation in adipose tissue is a contributing factor.

AIM

To test if GH/IGF1 promotes inflammation in adipocytes, and if this is relevant for systemic insulin resistance in acromegaly. Furthermore, to investigate the effect of treatment modalities (transsphenoidal surgery (TS), somatostatin analogs (SAs), and pegvisomant (PGV)) on glucose metabolism and inflammatory biomarkers in acromegaly.

METHODS

The in vitro effects of GH/IGF1 on gene expression of adipokines in human adipocytes were investigated. Body composition, glucose metabolism, and circulating adipokines (adiponectin (AD), high-molecular weight AD (HMWAD), leptin, vascular endothelial growth factor-A (VEGF-A), monocyte chemotactic protein 1 (MCP1), and thioredoxin (TRX)) were measured in 37 patients with active acromegaly before and after treatment.

RESULTS

In vitro GH, but not IGF1, increased VEGF and MCP1 in human adipocytes. In all treatment groups, body fat increased and IGF1 decreased to the same extent. Fasting glucose decreased in the TS (P=0.016) and PGV (P=0.042) groups, but tended to increase in the SA group (P=0.078). Insulin and HOMA-IR decreased in both TS and SA groups, while the PGV group showed no changes. Serum VEGF and MCP1 decreased significantly in the TS group only (P=0.010, P=0.002), while HMWAD increased with PGV treatment only (P=0.018). A multivariate analysis model identified the changes in GH and VEGF as predictors of improvement in HOMA-IR after treatment (R²=0.39, P=0.002).

CONCLUSIONS

i) GH directly promotes inflammation of human adipocytes by increasing VEGF and MCP1 levels; ii) glucose metabolism and inflammation (VEGF and MCP1) improve to some extent after treatment, despite an increase in adipose tissue mass; and iii) the decrease in insulin resistance after therapy in acromegaly depends, to some extent, on treatment modalities.

Evaluation of recurrence after photodynamic therapy with topical methylaminolaevulinate for 157 basal cell carcinomas in 90 patients

The aim of this study was to evaluate the effect of photodynamic therapy with topical methylaminolevulinate for the treatment of basal cell carcinomas in a single dermatological department. Ninety patients (34.4% men and 65.6% women) with a total of 157 basal cell carcinomas (111 superficial, 40 nodular, 6 unknown) were treated. Primary endpoint was clinically observed recurrence verified by biopsy 3, 6 and 12 months after treatment, then once a year. Estimated patient recurrence rates were 7% at 3 months, 19% at 6 months, 27% at 12 months and 31% at 24 months. Patients aged over 60 years had significantly higher estimated recurrence rates compared with patients aged 60 years or under (at 12 months, 35% vs. 19%, p?=?0.01). Estimated recurrence rates for tumours was 4% at 3 months, 11% at 6 months, 16% at 12 months and 19% at 24 months. There were significantly higher estimated recurrence rates for nodular basal cell carcinomas compared with superficial basal cell carcinomas (at 12 months, 28% vs. 13%, p?=?0.008). In conclusion, photodynamic therapy is only appropriate for treatment of superficial basal cell carcinoma, and, age above 60 years and histology showing nodular basal cell carcinoma are independent risk factors for developing a recurrent basal cell carcinoma.

The impact of pegvisomant treatment on substrate metabolism and insulin sensitivity in patients with acromegaly

CONTEXT

Pegvisomant is a specific GH receptor antagonist that is able to normalize serum IGF-I concentrations in most patients with acromegaly. The impact of pegvisomant on insulin sensitivity and substrate metabolism is less well described.

PATIENTS AND METHODS

We assessed basal and insulin-stimulated (euglycemic clamp) substrate metabolism in seven patients with active acromegaly before and after 4-wk pegvisomant treatment (15 mg/d) in an open design.

RESULTS

After pegvisomant, IGF-I decreased, whereas GH increased (IGF-I, 621 +/- 82 vs. 247 +/- 33 microg/liter, P = 0.02; GH, 5.3 +/- 1.5 vs. 10.8 +/- 3.3 microg/liter, P = 0.02). Basal serum insulin and plasma glucose levels decreased after treatment (insulin, 54 +/- 5.9 vs. 42 +/- 5.3 pmol/liter, P = 0.001; glucose, 5.7 +/- 0.1 vs. 5.3 +/- 0.0 mmol/liter, not significant), whereas palmitate kinetics were unaltered. During the clamp, the glucose infusion rate increased after pegvisomant (3.1 +/- 0.5 vs. 4.4 +/- 0.6 mg/kg.min, P = 0.02), whereas the suppression of endogenous glucose production tended to increase (0.7 +/- 0.0 vs. 0.5 +/- 0.1 mg/kg.min, not significant). Total resting energy expenditure decreased after pegvisomant treatment (1703 +/- 109 vs. 1563 +/- 101 kcal/24 h, P = 0.03), but the rate of lipid oxidation did not change significantly.

CONCLUSIONS

1) Pegvisomant treatment for 4 wk improves peripheral and hepatic insulin sensitivity in acromegaly. 2) This is associated with a decrease in resting energy expenditure, whereas free fatty acid metabolism is unaltered. 3) The data support the important direct effects of GH on glucose metabolism and add additional benefits to pegvisomant treatment for acromegaly.