Pituitary tumours without distinct lineage differentiation express stem cell marker SOX2.

CONTEXT: The recent WHO 2022 Classification of pituitary tumours identified a novel group of 'plurihormonal tumours without distinct lineage differentiation (WDLD)'. By definition, these express multiple combinations of lineage commitment transcription factors, in a monomorphous population of cells. OBJECTIVES: To determine the expression of stem cell markers (SOX2, Nestin, CD133) within tumours WDLD, immature PIT-1 lineage and acidophil stem cell tumours, compared with committed cell lineage tumours. METHODS: Retrospective evaluation of surgically resected pituitary tumours from St Vincent's Hospital, Sydney. Patients were selected to cover a range of tumour types, based on transcription factor and hormone immunohistochemistry. Clinical data was collected from patient files. Radiology reports were reviewed for size and invasion. Samples were analysed by immunohistochemistry and RT-qPCR for SF-1, PIT-1, T-PIT, SOX2, Nestin and CD133. Stem cell markers were compared between tumours WDLD and those with classically "mature" types. RESULTS: On immunohistochemistry, SOX2 was positive in a higher proportion of tumours WDLD compared with those meeting WHO lineage criteria, 7/10 v 10/42 (70 v 23.4%, p = 0.005). CD133 was positive in 2/10 tumours WDLD but 0/41 meeting lineage criteria, P = 0.003. On RT-qPCR, there was no significant difference in relative expression of stem cell markers (SOX2, CD133, Nestin) between tumours with and WDLD. CONCLUSIONS: Our study is the first to biologically characterise pituitary tumours WDLD. We demonstrate that these tumours exhibit a higher expression of the stem cell marker SOX2 compared with other lineage-differentiated tumours, suggesting possible involvement of stem cells in their development.

Measurement of neopterin, TGF-ß1 and ACE in the exhaled breath condensate of patients with sarcoidosis.

Exhaled breath condensate (EBC) is a non-invasive method of sampling airway lining fluids in respiratory diseases. This may be useful in identifying exhaled biomarkers of granulomatous inflammation and pulmonary fibrosis in patients with sarcoidosis. The aim of this pilot study was to identify markers of granulomatous airway inflammation and disease activity including neopterin, transforming growth factor-ß1 (TGF-ß1) and angiotensin converting enzyme (ACE) in EBC. EBC was collected from 16 patients with sarcoidosis and 22 healthy control subjects. EBC neopterin, and active-TGF-ß1 were measured by ELISA. EBC-ACE activity was measured using a colorimetric assay. EBC neopterin was detectable in 3/20 controls and 7/16 patients with sarcoidosis. Patients with sarcoidosis had greater mean neopterin levels compared to control subjects (0.57 ± 0.45 nmol l(-1) versus 0.41 ± 0.22 nmol l(-1), p = 0.04). TGF-ß1 was detectable in the EBC of all subjects and concentrations were higher in patients with sarcoidosis compared with controls (115.5 ± 79.6 pg mol(-1) versus 82.3 ± 16.2 pg mol(-1), p = 0.048). There was no difference in EBC ACE activity, which was only detectable in 3/20 healthy controls and 2/16 patients (p = 0.91). EBC markers of granulomatous inflammation are detectable at greater levels in patients with sarcoidosis compared to healthy controls subjects. Larger studies and development of sensitive assays are warranted to examine the disease correlates and predictive utility of these markers.

Ophthalmic pterygium: a stem cell disorder with premalignant features.

Pterygia are common ocular surface lesions thought to originate from limbal stem cells altered by chronic UV exposure. Traditionally regarded as a degenerative condition, pterygia also display tumor-like features, such as a propensity to invade normal tissue and high recurrence rates following resection, and may coexist with secondary premalignant lesions. This study was initiated to determine the rate of concurrent ocular surface diseases in patients with pterygia recruited from the practice of a single surgeon operating in a Sydney metropolitan hospital. One hundred pterygium specimens were histopathologically reviewed and selected cases were immunohistochemically assessed to confirm diagnosis. Along with previously documented typical features including epithelial proliferation, goblet cell hyperplasia, angiogenesis, inflammation, elastosis, stromal plaques, and Bowman's membrane dissolution, we identified five cases of ocular surface squamous neoplasia, six cases of primary acquired melanosis, two compound nevi (one suspect invasive melanoma), and one dermoid-like lesion. In 18 specimens, clusters of basal epithelial cells that coexpressed cytokeratin-15/-19 and p63-α were identified at the head of the pterygium, coinciding with clinical observation of Fuchs' flecks. Our data show that significant preneoplastic lesions may be associated with pterygium and that all excised pterygia should undergo histological examination. The presence of p63-α-positive epithelial cell clusters supports the hypothesis that pterygia develop from limbal epithelial progenitors.

The pathogenesis of pterygium: current concepts and their therapeutic implications.

Pterygium is a disease of the ocular surface that is associated with chronic UV exposure and is characterized by proliferation, inflammatory infiltrates, fibrosis, angiogenesis and extracellular matrix breakdown. Although pterygium is not fully understood, significant progress has been made toward understanding the mechanisms involved in its pathogenesis. In this review, we provide an update on the signaling pathways activated by UV light that result in induction of mediators responsible for the growth of pterygium. We also review the recent genetic studies on hereditary factors and provide a brief overview of the role of epithelial mesenchymal transition, bone marrow progenitor cells, and neuronal signals that may also contribute to the pathogenesis of pterygium. Therapeutic options for pterygium are discussed based on the mechanisms that perpetuate its growth.

Localization of the low-affinity nerve growth factor receptor p75 in human limbal epithelial cells.

Biological effects of nerve growth factor (NGF) are mediated through receptors known as nerve growth factor receptors (NGFR), which include p75 and TrkA. This study was initiated after identifying NGFR as an up-regulated gene in the limbus by cDNA microarray analysis and we postulate that its expression may be indicative of a stem/progenitor cell phenotype. Immunohistochemistry was performed on normal human adult (n=5) and foetal (n=3) corneal tissue using antibodies directed against p75, TrkA, NGF, p63, ABCG2 and CK3/12. Limbal, conjunctival and pterygium tissue was obtained from patients (n=10) undergoing pterygium resection and used for immunohistochemical assessment. Paraffin-embedded archival human skin specimens (n=4) were also evaluated. In vitro expression of NGFR was determined in limbal, conjunctival and pterygium-derived epithelial cells. p75 was selectively expressed by basal epithelial cells in pterygia, conjunctiva and limbus, but was absent in the central cornea. These results were confirmed with two additional p75 specific antibodies. In contrast, TrkA was found in full-thickness pterygium, conjunctival, limbal and corneal epithelium in both adult and foetal eyes. p75 expression was identified in a small percentage, while TrkA was found on the entire population of cultured conjunctival, limbal and pterygium-derived epithelial cells. This receptor was also observed in selective regions of the human epidermis and hair follicle bulge. Our results illustrate the selective expression of p75 in basal pterygium, conjunctival and limbal epithelium, while staining was absent in adult and foetal central cornea. p75 may represent an additional ocular surface epithelial stem/progenitor cell signature gene.

Cultured human ocular surface epithelium on therapeutic contact lenses.

BACKGROUND: This study was initiated after observation of some intriguing epithelial growth properties of contact lenses used as a bandage for patients after pterygium surgery. AIM: To determine the efficacy of culturing human ocular surface epithelial cells on therapeutic contact lenses in autologous serum with a view of using this system to transfer epithelial cells to patients with persistent corneal or limbal defects. METHODS: Excess graft tissue resected from patients undergoing pterygium surgery (n = 3) consisting of limbal epithelium was placed on siloxane-hydrogel contact lenses (lotrafilcon A and balafilcon A). Limbal explants were cultured in media with 10% autologous serum. Morphology, proliferative capacity and cytokeratin profile were determined by phase contrast, light and electron microscopy, and immunohistochemical analysis. RESULTS: Lotrafilcon A contact lenses sustained proliferation and migration from limbal tissue. Cells became confluent after 10-14 days and consisted of 2-3 layers with a corneal phenotype (CK3(+)/CK12(+)/CK19(-)) and a propensity to proliferate (p63(+)). Electron microscopy showed microvilli on the apical surface with adhesive projections, indicating that these cells were stable and likely to survive for a long term. Growth was not observed from limbal explants cultured on balafilcon A contact lenses. CONCLUSION: A method for culturing human ocular surface epithelium on contact lenses that may facilitate expansion and transfer of autologous limbal epithelial cells while avoiding the risks associated with transplanting allogeneic tissue has been developed. This technique may be potentially useful for the treatment of patients with limbal stem cell deficiency.