2004, Vol.17, No.4

Anatomy & Biological Anthropology 2023 KCI Impact Factor : 0.33

pISSN : 2671-5651 / eISSN : 2671-566X
https://journal.kci.go.kr/aba

The homeostasis of microenvironment in central nervous system, essential for normal function, is maintained by blood-brain barrier (BBB). ZO-1 in tight junctions (TJs) plays an important role in maintaining BBB endothelial ion and solute barriers. Malfunction of BBB by reactive oxygen species has been attributed to disruption of TJs. This study examined H2O2 effects on paracellular permeability and changes in TJ protein ZO-1 using primary culture of bovine brain microvessel endothelial cells. The BBB permeability,measured as TER, increased in a dose-and time-dependent manner when treated with H2O2 (0.01, 0.1, 1.0 mM). Cytotoxicity test revealed that H2O2 did not cause cell death below 1 mM H2O2 within 4 hr. H2O2 caused intermittent disruption and loss of ZO-1 at tight junctions, but ZO-1 maintained steady state levels of expression. In conclusion, we report that H2O2 induces increased paracellular permeability of BBB that is accompanied with alterations in localization of ZO-1.

Interstitial Cells of Cajal (ICC) are pacemaker cells that generates slow waves and drive spontaneous mechanical contractions of gastrointestinal smooth muscle. Slow waves are generated the periodic activation of spontaneous inward currents (pacemaker currents). We studied the modulation of pacemaker activities by bradykinin (10-8 M) in cultured ICC with the whole cell patch-clamp technique, and the localization of bradykinin-2 receptor-immunoreactivity using double labelling immunohistochemistry in the murine small intestine. Externally applied bradykinin produced membrane depolarization in current-clamping mode. At a -70 mV of holding potential bradykinin increased tonic inward pacemaker currents. Double labelling with bradykinin-2 receptor and and c-kit was shown that ICC expressed the bradykinin-2 receptor-immunoreactivity. These results suggest that bradykinin modulates electrical activities of ICC via bradykinin-2 receptor, which may regulate gastrointestinal motility.

A previous report by this laboratory demonstrated that bacterial iron chelator (siderophore) triggers inflammatory signals, including the production of CXC chemokine IL-8, in human intestinal epithelial cells (IECs). Microarraybased gene expression profiling revealed that iron chelator also induces CC chemokine MIP-3α/CCL20. As CCL20 is chemotactic for the cells involved in host adaptive immunity, this suggests that iron chelator may stimulate IECs to have the capacity to link mucosal innate and adaptive immunity. The basal medium from iron chelator deferoxamine (DFO)-treated HT-29 monolayers was as chemotactic as rhCCL20 at equivalent concentrations to attract CCR6± cells. The increase of CCL20 protein secretion appeared to correspond to that of CCL20 mRNA levels, as determined by real-time quantitative RT-PCR. The efficacy of DFO at inducing CCL20 mRNA was also observed in human Peripheral Blood Mononuclear Cells (PBMCs) and in THP-1 cells, but not in Human Umbillical Vein Endothelial Cells (HUVECs). Interestingly, unlike other proinflammatory cytokines, such as TNF-α and IL-1β, a time-dependent experiment revealed that DFO slowly induces CCL20, suggesting a novel mechanism of action. A pharmacologic study also revealed that multiple signaling pathways are differentially involved in CCL20 production by DFO, while some of those pathways are not involved in TNF-α-induced CCL20 production. Collectively, these results demonstrate that, in addition to some bacterial products known to induce host adaptive immune responses, direct chelation of host iron by infected bacteria may also contribute to the initiation of host adaptive immunity in the intestinal mucosa.