A Pro-Endocrine Pancreatic Islet Transcriptional Program Established During Development Is Retained in Human Gallbladder Epithelial Cells

BACKGROUND & AIMS

Pancreatic islet β-cells are factories for insulin production; however, ectopic expression of insulin also is well recognized. The gallbladder is a next-door neighbor to the developing pancreas. Here, we wanted to understand if gallbladders contain functional insulin-producing cells.

METHODS

We compared developing and adult mouse as well as human gallbladder epithelial cells and islets using immunohistochemistry, flow cytometry, enzyme-linked immunosorbent assays, RNA sequencing, real-time polymerase chain reaction, chromatin immunoprecipitation, and functional studies.

RESULTS

We show that the epithelial lining of developing, as well as adult, mouse and human gallbladders naturally contain interspersed cells that retain the capacity to actively transcribe, translate, package, and release insulin. We show that human gallbladders also contain functional insulin-secreting cells with the potential to naturally respond to glucose in vitro and in situ. Notably, in a non-obese diabetic (NOD) mouse model of type 1 diabetes, we observed that insulin-producing cells in the gallbladder are not targeted by autoimmune cells. Interestingly, in human gallbladders, insulin splice variants are absent, although insulin splice forms are observed in human islets.

CONCLUSIONS

In summary, our biochemical, transcriptomic, and functional data in mouse and human gallbladder epithelial cells collectively show the evolutionary and developmental similarities between gallbladder and the pancreas that allow gallbladder epithelial cells to continue insulin production in adult life. Understanding the mechanisms regulating insulin transcription and translation in gallbladder epithelial cells would help guide future studies in type 1 diabetes therapy.

The miR-30 family microRNAs confer epithelial phenotype to human pancreatic cells

Epithelial-to-mesenchymal transition is a phenomenon necessary for embryonic development and also seen during certain pathological conditions.  We show here for the first time that reduction in miR-30 family microRNAs, is responsible for mesenchymal transition of primary cultures of human pancreatic epithelial cells.  We found that miR-30 family microRNAs target mesenchymal gene transcripts and maintain them in a translationally inactive state.  Forced depletion using miR-30 family specific anti-miRs leads to mesenchymal transition while ectopic overexpression maintains the epithelial phenotype.  We also show that miR-30 family microRNAs increase in abundance during differentiation of pancreatic islet-derived mesenchymal cells into hormone-producing islet-like cell aggregates.  Our studies in human adult diseased pancreas also demonstrate that miR-30 family microRNAs are expressed at lower abundance in fibrotic lesions during pancreatitis.  Together, our data confirm that miR-30 family microRNAs form a part of the regulatory signaling events involved in cellular response of pancreatic epithelial cells during mesenchymal transition.

Human fetal pancreatic insulin-producing cells proliferate in vitro

There have been considerable efforts towards understanding the potential of human pancreatic endocrine cells to proliferate and transition into mesenchymal cell populations. Since rodent studies have demonstrated that mouse insulin-producing cells do not proliferate in vitro, a similar possibility has been considered for human islet endocrine cells. Considering the inherent differences in mouse and human pancreatic islets, we decided to assess the potential of human fetal pancreatic insulin-producing cells to proliferate in vitro. We studied the proliferative potential of human fetal pancreatic islet-derived populations from second or third trimester fetal pancreas and characterized the cells that grow out during their expansion. We have used seven different approaches including in situ hybridization and immunostaining, quantitative estimation of multiple gene transcripts in populations as well as in single cells, clonal analysis of islet cells, assessment of heritable marks of active insulin promoter, and thymidine analog-based lineage tracing. Our studies demonstrate that human fetal pancreatic insulin-producing cells proliferate in vitro to generate mesenchymal cell populations. Interestingly, epigenetic modifications that mark open chromatin conformation of insulin promoter regions are retained even after a million fold expansion/proliferation in vitro. These findings demonstrate that hormone-producing cells in pancreatic islets proliferate in vitro and retain epigenetic marks that characterize an active insulin promoter. Such in vitro-derived mesenchymal cells may be of potential use in cell-replacement therapy for diabetes.

Expression of islet-specific microRNAs during human pancreatic development

During pancreatic islet development, sequential changes in gene expression are known to be necessary for efficient differentiation and function of the endocrine pancreas. Several studies till now have demonstrated that microRNAs (miRNAs), which regulate translation of gene transcripts, influence gene expression cascades involved in pancreas development. Some of these miRNAs; miR-7 and miR-375 have been known to be expressed at high levels in pancreas and are also known to be involved in Zebrafish pancreas development as well as insulin secretion in mice. We demonstrate here that 4 different islet-specific microRNAs (miR-7, miR-9, miR-375 and miR-376) are expressed at high levels during human pancreatic islet development. Of these, miR-375, is seen to be differentially expressed in human islet beta- as well as non-beta-cells. Though no significant difference in abundance of miR-375 was noted in either cell type, analysis of islet-specific miRNA and mRNA in single cells show that non-beta cells contain higher levels of miR-375. Our data demonstrate that miRNAs that are known to be regulated during Zebrafish pancreatic development may play similar role in human pancreatic islet development.

Fatal Clostridium perfringens infection of a liver cyst

We report a case of Clostridium perfringens infection of a pre-existing hepatic cyst leading to a fatal outcome.

Acute pancreatitis presenting as a case of splenic rupture

A31-year-old woman, who had experienced some epigastric pains 10 days earlier, presented acutely with upper abdominal pain of 24 hours duration. There was associated nausea and vomiting. She had a past history of depression and excess alcohol consumption. Her only medication was ibuprofen for joint pains.

Mesotheliomas with deciduoid morphology: a morphologic spectrum and a variant not confined to young females

Deciduoid mesotheliomas are rare with only four previously reported cases, all affecting the peritoneum of young females. We describe another six cases (three men and three women; age range 52-65 yrs, median 55 yrs; five peritoneal and one pleural). Three patients had an occupational history of asbestos exposure. The deciduoid appearance predominated in four cases, whereas in two it represented a minor component within conventional tubulopapillary epithelioid mesothelioma. All tumors were strongly cytokeratin-positive (including CK5/6) and all showed at least focal staining for thrombomodulin, HBME-1, and calretinin. All were negative for epithelial mucin (D/PAS), CEA, BerEP4, LeuM1 (CD15), CD21, CD35, and S100 protein. Five of six cases (83%) were vimentin-positive and two (33%) were focally positive for alpha-smooth muscle actin. A differential diagnosis of gastrointestinal autonomic nerve tumor (GANT) had been initially considered from the morphology of one case, and we found positivity for some of the "neuronal" markers described in GANTs. This prompted us to apply such a panel to the other five tumors, accepting that the cytokeratin positivity encountered in all of our cases would exclude GANT. All cases of deciduoid mesothelioma (100%) were positive for PGP 9.5 and NSE and four of six (66%) were positive for NKI/C3. Weak focal staining (<5% cells) for synaptophysin was seen in two of six tumors. All cases were chromogranin-negative. All cases examined by electron microscopy showed desmosomes and smooth microvilli without rootlets but no neuroendocrine granules. In conclusion, a deciduoid morphology appears to be part of the histopathologic spectrum encountered in epithelioid mesothelioma. This variant is not confined to female patients and occurs over a wider age range than previously recognized. The overlapping immunophenotype with GANTs illustrates that caution should be exercised when interpreting positivity for "neuronal" markers in this context. An immunohistochemical panel that includes cytokeratins should always be used.

Carcinosarcoma of the urinary bladder. A light, immunohistochemical and electron microscopical case report

A case of urinary bladder carcinosarcoma (UBCS) is reported with light, immunohistochemical and electron microscopical findings. The tumour consisted of a squamous cell carcinoma, variable spindle cell stromal elements compatible with fibrosarcoma, and rhabdomyoblasts. Intermediate filament co-expression of cytokeratin and vimentin was shown by immunohistochemistry. Electron microscopy (EM) confirmed the nature of the three components, and indicated some similarities between the three cell-types present. Comparisons with the previous UBCS in the literature are made.

Rhabdoid tumour of the bladder: a histological, ultrastructural and immunohistochemical study

A rapidly fatal bladder tumour which had the features of a rhabdoid tumour was studied by sequential biopsies and at autopsy. This is the first rhabdoid tumour recorded at this site and the first in which there was co-existent transitional cell carcinoma. The possibility that rhabdoid tumour is histogenetically heterogeneous is discussed.

An outbreak of respiratory syncytial virus infection in a continuing-care geriatric ward

A small outbreak of respiratory syncytial virus infection in a continuing-care geriatric ward during the period December 1982 to March 1983 is reported. It demonstrates that respiratory syncytial virus infection can cause serious lower respiratory tract infection even in patients without any previous history of chest disease.

Cerebellar astrocytomas in children and young adults

A clinical and pathological review of 43 cases of cerebellar astrocytomas in children and young adults was undertaken. Thirty-one of the 36 surviving patients were examined by computed tomography. Twelve patients with asymptomatic tumour were detected. Histology was necessary to identify the higher risk "diffuse" group, but no histological features helped to identify tumours liable to recur. Improvements in the prognosis may occur with long term CT scanning.

Metastasis of carcinoma to meningioma and glioma

A case of frontal meningioma harbouring a metastasis from a previously treated breast carcinoma, and a case of metastatic carcinoma into a frontal glioma are reported.

Cellolite (Merocel): a new form of neurosurgical patty. Evaluation of histological responses in rats

Cellolite and cottonoid were compared with regard to histological reactions provoked when they were left in contact with the rat brain. Pieces of each material were implanted in 27 rats either extra- or intracerebrally for 48 hours or 28 days. Histological findings suggest that the use of Cellolite for neurosurgery would be unlikely to cause adverse reactions any worse than those caused by cottonoid.

Barrier properties of vernix caseosa

Experiments are described which show that vernix caseosa has a mechanical barrier effect if it is deposited in an unbroken layer. Specific antibacterial properties were not detected in vernix. It is suggested that vernix is best left on a newborn infant because of its mechanical obstruction to bacterial passage.

Haemangioma of the fallopian tube. Case report

I present the sixth report of a patient with a haemangioma of the Fallopian tube and the first from the United Kingdom. The patient presented with an acute abdomen due to haemoperitoneum.