Connie Hau Yan Wong

Plasticity of rat bone marrow-derived 5-hydroxytryptamine-sensitive neurons: dedifferentiation and redifferentiation

Inducing cellular dedifferentiation has been proposed as a potential method for enhancing endogenous regeneration in mammals. Here we demonstrate that phenotypic and functional neurons derived from adult rat bone marrow stromal stem cells (MSCs) can be induced to undergo dedifferentiation, then proliferation and redifferentiation. In addition to morphological changes and expression of neuronal markers, neuron‐specific enolase and neurofilament H, functional differentiation was monitored by intracellular Ca2+ mobilization in response to a ubiquitous neurotransmitter, 5‐hydroxytryptamine (5‐HT) at different stages. The neurons derived from rMSCs were found to have increased 5‐HT response. This 5‐HT sensitivity could be reversed to basal level similar to that found in rMSCs when neurons, up to 3 days after neuronal induction, were induced to undergo dedifferentiation. Increase in 5‐HT‐induced Ca2+ mobilization was again observed when rMSCs derived from dedifferentiated neurons were induced to redifferentiate into neurons again. Variation in 5‐HT1A receptor immunoreactivity was observed in stem cells, differentiated neurons, dedifferentiated neurons and redifferentiation neurons, consistent with their respective 5‐HT sensitivity. These results suggest that adult bone marrow‐derived 5‐HT sensitive neurons are capable of dedifferentiation, then proliferation and redifferentiation, indicating their plasticity and potential use in treatment of neural degenerative diseases.

CFTR is required for cellular entry and internalization of Chlamydia trachomatis

Chlamydia trachomatis is an obligate intracellular Gram‐negative pathogen affecting over 600 million people worldwide with 92 million new cases occurring globally each year. C. trachomatis enter the cells and replicate to infect different tissues/organs, giving rise to a spectrum of pathological conditions; however, the exact mechanism or receptor(s) for their entry is not well understood. Here we report that CFTR (cystic fibrosis transmembrane conductance regulator), an apical epithelial anion channel, is required for cellular entry and internalization of C. trachomatis. Human epithelial cell lines expressing functional CFTR internalized more C. trachomatis than the cells expressing mutant Δ508 CFTR. The in vitro cellular uptake of C. trachomatis can be blocked by CFTR inhibitors or antibody, and the in vivo cellular uptake of C. trachomatis in CFTR mutant (CFTR−/−) mice was significantly less compared with that in the wild‐type. Direct interaction between CFTR and C. trachomatis LPS (lipopolysaccharide) is demonstrated by their immune‐co‐localization and co‐immunoprecipitation. Despite an increase in CFTR expression observed upon C. trachomatis LPS challenge, a reduction in its ion channel activity is observed, consistent with the notion that CFTR functions as a receptor for cellular entry and internationization of C. trachomatis, with compromised ion‐channel function. These findings, for the first time, demonstrate that CFTR functions as a cell‐surface receptor for epithelial cell entry, and internalization of C. trachomatis and these findings may lead to the development of new treatment strategies to curtail the spread of chlamydial infections.

Involvement of cystic fibrosis transmembrane conductance regulator (CFTR) in the pathogenesis of hydrosalpinx induced by Chlamydia trachomatis infection

Background:  Genital Chlamydia (C) trachomatis infection has been recognized as the single most common cause of pelvic inflammatory disease leading to severe tubal damage, ectopic pregnancy, infertility and hydrosalpinx. However, the mechanism underlying the formation of hydrosalpinx induced by C. trachomatis infection remains largely unknown. We performed this study to determine the involvement of cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP‐activated chloride channel that regulates epithelial electrolyte and fluid secretion, in hydrosalpinx fluid formation.

Involvement of cystic fibrosis transmembrane conductance regulator in infection-induced edema

Abnormal fluid accumulation in tissues, including the life‐threatening cerebral and pulmonary edema, is a severe consequence of bacteria infection. Chlamydia (C.) trachomatis is an obligate intracellular gram‐negative human pathogen responsible for a spectrum of diseases, causing tissue fluid accumulation and edema in various organs. However, the underlying mechanism for tissue fluid secretion induced by C. trachomatis and most of other infectious pathogens is not known. Here, we report that in mice C. trachomatis infection models, the expression of cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP activated chloride channel, is up regulated together with increased cytokine release and tissue fluid accumulation that can be reversed by treatment with antibiotic specific for C. trachomatis and CFTR channel blocker. However, C. trachomatis infection cannot induce tissue edema in CFTR tm1Unc mutant mice. Administration of exogenous IL‐1β to mice mimics the C. trachomatis infection‐induced CFTR upregulation, enhanced CFTR channel activity and fluid accumulation, further confirming the involvement of CFTR in infection‐induced tissue fluid secretion.

Nucleotide-evoked ion transport and [Ca2+]i changes in normal and hyperhidrotic human sweat gland cells

Apical and basolateral application of ATP and UTP evoked [Ca(2+)](i) and short circuit current (Isc) increases in normal and hyperhidrotic human eccrine sweat gland cells grown into functionally polarised epithelia on permeable supports. Basolateral application to hyperhidrotic cells exhibited a markedly greater increase in Isc than in normal cells. Hyperhidrotic cells also demonstrated differences from the normal in [Ca(2+)](i) and Isc responses to ATP when pre-treated with thapsigargin. The data demonstrate the presence of apical and basolateral receptors that allow nucleotides to increase [Ca(2+)](i) and Isc. The results suggest that changes from the normal in transepithelial ion transport contribute to the characteristic excessive fluid production of hyperhidrotic sweat glands.