Nox4-mediated ROS production is involved, but not essential for TGFß-induced lens EMT leading to cataract.

The reactive oxygen species (ROS) producing enzyme, NADPH oxidase 4 (Nox4), is upregulated in response to TGFß in lens epithelial cells in vitro, and its selective inhibition was shown to block aspects of TGFß-induced epithelial-mesenchymal transition (EMT). In the present in situ study we validate the role(s) of Nox4 in TGFß-induced lens EMT leading to anterior subcapsular cataract (ASC) formation. Mice overexpressing TGFß in the lens, that develop ASC, were crossed to Nox4-deficient mice. When comparing mice overexpressing TGFß in lens, to mice that were also deficient for Nox4, we see the delayed onset of cataract, along with a delay in EMT protein markers normally associated with TGFß-induced fibrotic cataracts. In the absence of Nox4, we also see elevated levels of ERK1/2 activity that was shown to be required for TGFß/Smad2/3-signaling. qRT-PCR revealed upregulation of Nox2 and its regulatory subunit in TGFß-overexpressing lens epithelial cells devoid of Nox4. Taken together, these findings provide an improved platform to delineate putative Nox4 (and ROS) interactions with Smad2/3 and/or ERK1/2, in particular in the development of fibrotic diseases, such as specific forms of cataract.

Keratinocyte growth factor receptor is up-regulated in cyclosporin A-induced gingival hyperplasia.

Keratinocyte growth factor stimulates the growth and activity of epithelial cells via the keratinocyte growth factor receptor. We have recently shown that the growth factor is markedly elevated in cyclosporin A-induced gingival hyperplasia tissue in vivo, but the effects of cyclosporin A on the receptor are not yet known. The present study was therefore carried out to determine whether expression of the keratinocyte growth factor receptor is up-regulated in gingival hyperplasia compared with normal gingiva. Using immunohistochemistry and the reverse-transcribed polymerase chain-reaction, we obtained results which showed that receptor antigen and gene transcript levels were both elevated in gingival hyperplasia tissue. In addition, flow cytometry and the reverse-transcribed polymerase chain-reaction showed that the receptor and mRNA were also higher in gingival epithelial cells following incubation with cyclosporin A in vitro. These findings suggest that the keratinocyte growth factor-receptor pathway of mesenchymal-epithelial interaction could play an important part in the molecular pathogenesis of gingival hyperplasia.

Upregulation of keratinocyte growth factor in cyclosporin A-induced gingival overgrowth.

BACKGROUND: Drug-induced gingival overgrowth (GO) is a frequent and adverse side-effect associated principally with the administration of the immunosuppressive drug cyclosporin A (CsA) and also certain anti-epileptic and anti-hypertensive drugs. It is characterized by a marked increase in the thickness of the epithelial layer and the accumulation of excessive amounts of connective tissue. Although the mechanism by which the drugs cause GO is not yet understood, keratinocyte growth factor (KGF), which is a potent epithelial cell mitogen, has been implicated in other hyperplastic conditions, including mammary and prostatic hyperplasia, and could also be involved in the molecular pathology of GO. METHODS: Immunohistochemistry was used to examine the expression of KGF in normal gingiva (NG) and GO tissue sections. The relative level of KGF mRNA in GO tissue and cells was compared with that of NG tissue and fibroblast cells using the semi-quantitative reverse transcribed-polymerase chain reaction (RT-PCR) and DNA sequencing was carried out to confirm the identity of the PCR product. RESULTS: KGF antigen and mRNA were readily detected in the GO tissue immunohistochemically and by RT-PCR, respectively, but were not expressed in the NG tissue. Moreover, KGF transcripts were found to be approximately 2 times higher in the GO than in the NG fibroblasts in vitro, although the difference was not statistically significant. CONCLUSIONS: This study has shown, for the first time, that the level of KGF is elevated in GO and suggests that KGF may have an important role in the enhanced epithelial proliferation associated with GO.

Up-regulation of keratinocyte growth factor and receptor: a possible mechanism of action of phenytoin in wound healing.

A number of studies suggest that keratinocyte growth factor (KGF) plays a major part in reepithelialisation after injury, via binding to the specific KGF receptor (KGFR). Several pharmacological agents, including the anti-epileptic drug phenytoin (PHT), have been widely used clinically to promote wound healing. Although the mechanism of action of PHT in this process is still not well understood, it is possible that the activity of PHT in wound healing is mediated via KGF and the KGFR. In the present study, using the enzyme-linked immunosorbant assay and flow cytometry we have shown that PHT increases KGF secretion and KGFR expression by more than 150% in gingival fibroblasts and epithelial cells, respectively. Moreover, semi-quantitative reverse transcriptase-polymerase chain reaction analysis showed that PHT also markedly increased both KGF and KGFR gene transcription by these cells. Our findings thus suggest that the wound healing activity of PHT in vivo may be mediated, at least partly, via KGF and its receptor.

Keratinocyte growth factor is upregulated by the hyperplasia-inducing drug nifedipine.

Keratinocyte growth factor (KGF) is the seventh member of the fibroblast growth factor (FGF) family. It is produced by mesenchymal cells and its activity is specific for epithelial cells, controlling epithelial homeostasis and wound repair in a paracrine manner. Although KGF has been implicated in a number of hyperplastic pathologies, it has not previously been investigated in gingival hyperplasia (GH), an adverse side-effect of three pharmacologically different types of drugs, including the anti-hypertensive drug nifedipine (NIF). The mechanism by which NIF causes GH is not yet known, but we have recently shown that KGF mRNA transcripts are elevated in drug-induced GH in vivo (manuscript submitted). It is therefore possible that the action of NIF is mediated via KGF and, in the present study, using the enzyme-linked immunosorbent assay (ELISA) and the semi-quantitative reverse transcribed-polymerase chain reaction (RT-PCR), we found that NIF upregulates KGF secretion and gene transcription by gingival fibroblasts in vitro. Our results thus suggest that KGF may have an important role in the molecular pathology of GH in vivo.

A giant pedunculated tumor (Fibrolipoma) of oesophagus - a rare case.

A giant pedunculate tumour of oesophagus is reported in this study for its rareness.A mate patient aged 48 years was admitted at Jorhat Christian Medical Centre with the complaint of swelling of the neck and dysphagia for a period of 4 months. Clinically the neck swelling looks like swelling of left lobe of thyroid with intrathoracic extension, ENT examination was normal The barium Swallow X-ray of oesophagus showed surprisingly huge dilatation of upper half of the oesophagus. The oesophagoscopy snowed a large mobile infra oesophageal tumour extending from the upper end of the oesophagus upto the mid thoracic region. The neck is explored by collar incission and the cervical oesophagus is opened by longitudinal incission. The tumour is pulled out from the oesophagus and is removed completely by cutting the peduncle which was attached to the tight wall of the oesophagus just below the cricopharynx. The peduncle was about I em in diameter., The length of the tumour was about 3-4 cm at the thoracic part. Post Operative recovery was uneventful. The histopathology report skewed it to be a ease of FIBROLIPOMA.