Skin fibroblast activity in pretibial myxoedema and the effect of octreotide (Sandostatin) in vitro

The tumour microenvironment of pituitary neuroendocrine tumours

The tumour microenvironment (TME) includes a variety of non-neoplastic cells and non-cellular elements such as cytokines, growth factors and enzymes surrounding tumour cells. The TME emerged as a key modulator of tumour initiation, progression and invasion, with extensive data available in many cancers, but little is known in pituitary tumours. However, the understanding of the TME of pituitary tumours has advanced thanks to active research in this field over the last decade. Different immune and stromal cell subpopulations, and several cytokines, growth factors and matrix remodelling enzymes, have been characterised in pituitary tumours. Studying the TME in pituitary tumours may lead to a better understanding of tumourigenic mechanisms, identification of biomarkers useful to predict aggressive disease, and development of novel therapies. This review summarises the current knowledge on the different TME cellular/non-cellular elements in pituitary tumours and provides an overview of their role in tumourigenesis, biological behaviour and clinical outcomes.

Visualisation of interstitial lung disease by molecular imaging of integrin αvβ3 and somatostatin receptor 2

OBJECTIVE

To evaluate integrin αvβ3 (alpha-v-beta-3)-targeted and somatostatin receptor 2 (SSTR2)-targeted nuclear imaging for the visualisation of interstitial lung disease (ILD).

METHODS

The pulmonary expression of integrin αvβ3 and SSTR2 was analysed in patients with different forms of ILD as well as in bleomycin (BLM)-treated mice and respective controls using immunohistochemistry. Single photon emission CT/CT (SPECT/CT) was performed on days 3, 7 and 14 after BLM instillation using the integrin αvβ3-targeting ¹⁷⁷Lu-DOTA-RGD and the SSTR2-targeting ¹⁷⁷Lu-DOTA-NOC radiotracer. The specific pulmonary accumulation of the radiotracers over time was assessed by in vivo and ex vivo SPECT/CT scans and by biodistribution studies.

RESULTS

Expression of integrin αvβ3 and SSTR2 was substantially increased in human ILD regardless of the subtype. Similarly, in lungs of BLM-challenged mice, but not of controls, both imaging targets were stage-specifically overexpressed. While integrin αvβ3 was most abundantly upregulated on day 7, the inflammatory stage of BLM-induced lung fibrosis, SSTR2 expression peaked on day 14, the established fibrotic stage. In agreement with the findings on tissue level, targeted nuclear imaging using SPECT/CT specifically detected both imaging targets ex vivo and in vivo, and thus visualised different stages of experimental ILD.

CONCLUSION

Our preclinical proof-of-concept study suggests that specific visualisation of molecular processes in ILD by targeted nuclear imaging is feasible. If transferred into clinics, where imaging is considered an integral part of patients' management, the additional information derived from specific imaging tools could represent a first step towards precision medicine in ILD.

Pseudoacromegaly induced by the long-term use of minoxidil

Acromegaly is an endocrine disorder caused by chronic excessive growth hormone secretion from the anterior pituitary gland. Significant disfiguring changes occur as a result of bone, cartilage, and soft tissue hypertrophy, including the thickening of the skin, coarsening of facial features, and cutis verticis gyrata. Pseudoacromegaly, on the other hand, is the presence of similar acromegaloid features in the absence of elevated growth hormone or insulin-like growth factor levels. We present a patient with pseudoacromegaly that resulted from the long-term use of minoxidil at an unusually high dose. This is the first case report of pseudoacromegaly as a side effect of minoxidil use.

Pretibial myxoedema associated with Hashimoto's thyroiditis

Pretibial myxoedema is a cutaneous mucinosis typically associated with Graves' disease, although it may also develop in subjects with non-thyrotoxic thyroid pathologies. This report presents a rare case of pretibial myxoedema occurring in a 58-year-old woman with biopsy-proven Hashimoto's thyroiditis. The hypothetical pathogenetic link between the two disorders is discussed with particular attention to the role of thyroid stimulating hormone receptor antibodies.

Refractory pretibial myxoedema with response to intralesional insulin-like growth factor 1 antagonist (octreotide): downregulation of hyaluronic acid production by the lesional fibroblasts

We report a case of refractory pretibial myxoedema (PTM) with Graves' disease in which there was a good clinical response to intralesional injection of the insulin-like growth factor 1 (IGF-1) antagonist octreotide. Intralesional octreotide (200 microg once daily) dramatically improved the tumorous lesions of PTM after 4 weeks, and the lesions remained stable even after reducing the dose to 200 microg once weekly. The amount of hyaluronic acid (HA) in the lesional skin decreased to 5.8 microg mg-1 dry weight from 16.3 microg mg-1 dry weight after 4 weeks of octreotide treatment. IGF-1 showed a dose-dependent stimulatory effect on HA secretion by both normal and patient's fibroblasts at higher concentrations in vitro. Octreotide significantly suppressed IGF-1 induced-HA secretion by the patient's fibroblasts, but not by normal fibroblasts, which suggests that expression of IGF-1 receptor on fibroblasts, or its affinity for IGF-1, are upregulated in PTM, resulting in the oversecretion of HA. These results might suggest that octreotide improves PTM through downregulation of HA production by lesional fibroblasts.

Antiproliferative effects and insulin-like growth factor-I expression in Balb-C 3T3 fibroblasts after treatment with somatostatin and gonadotropin-releasing hormone analogs

The present study was aimed to compare antiproliferative effects of somatostatin (SS) and gonadotropin-releasing hormone analogs (GnRHa) on a fibroblast cell line. Proliferation index, cell count, viability of the cells and insulin-like growth factor-I (IGF-I) immunoreactivity were determined after treatment with either SS (100 microM/ml), GnRHa (35 nM/ml) or SS and GnRHa of Balb-C 3T3 mouse fibroblasts. It was found that the proliferation index, cell count, viability and IGF-I immunoreactivity were not affected by GnRHa treatment as compared with no treatment (p > 0.05). Application of SS to the fibroblasts resulted in a significant reduction in proliferation index, cell count, and IGF-I immunoreactivity as compared with GnRHa treatment and no treatment, but it had no effect on cell viability. The labelling index in SS-treated cells was significantly reduced as compared with combined treatment with SS and GnRHa. In conclusion, a direct effect of GnRHa on fibroblast cells in culture could not be demonstrated. SS had direct inhibitory effects on cell proliferation possibly via inhibition of IGF-I effects without affecting cell viability.

Pretibial myxoedema presenting as a scar infiltrate

A 41-year-old man developed pretibial myxoedema localized to scars following treatment for hyperthyroidism. Pre-existing scars on both lower legs, present for more than 20 years, were infiltrated with firm and nonpitting nodules and plaques over his shins. The clinical presentation of this patient highlights pretibial myxoedema as a cause of scar infiltration. The pathogenesis of pretibial myxoedema is reviewed.

Graves' disease presenting as localized myxedema in a thigh donor graft site

Pretibial myxedema, exophthalmus, and thyroid acropachy are the classic manifestations of Graves' Disease. However, myxedema in Graves' Disease can occur in locations other than the pretibial surfaces. Furthermore, with systemic symptoms, localized myxedema may occur at sites of trauma or scarring. We describe a patient with localized myxedema on the thigh at the site of a donor skin graft as the initial presentation of Graves' Disease.

Successful surgical treatment of severe pretibial myxoedema

We report a 46-year-old man with severe and long-standing pretibial myxoedema, who responded well to local surgical treatment. This improvement has been maintained over a 12-month period, perhaps because of concomitant treatment with octreotide.