SUMMARYBlood-brain barrier (BBB) is a dynamic interference that regulates the nutrition and toxic substance in and out of the central nervous system (CNS), and plays a crucial role in maintaining a stable circumstance of the CNS. Tight junctions among adjacent cells form the basic structure of BBB to limiting paracellular permeability. In the present review, the constituents of tight junction proteins are depicted in detail, together with the regulation of tight junction under stimulation and in pathological conditions. Tight junction modulators are also discussed.

Despite advances in controlled drug delivery, reliable methods for activatable, high-resolution control of drug release are needed. We hypothesized that the photothermal effect mediated by a near-infrared (NIR) laser and hollow gold nanospheres (HAuNS) could modulate the release of anticancer agents. We tested this hypothesis by developing biodegradable and biocompatible microspheres (1~15 µm) containing the antitumor drug paclitaxel (PTX) and HAuNS (~35 nm in diameter) displaying surface plasmon absorbance in the near-infrared (NIR) region. HAuNS-containing microspheres exhibited an NIR light-induced thermal effect similar to that of plain HAuNS. Rapid, repetitive PTX release from the PTX/HAuNS-containing microspheres was observed when microspheres were irradiated with NIR light (808 nm), whereas PTX release became insignificant when NIR light was switched off. The release of PTX from the microspheres could be readily controlled by NIR laser output power, duration of laser irradiation, treatment frequency, and the concentration of HAuNS embedded inside the microspheres. In vitro, cancer cells incubated with PTX/HAuNS-loaded microspheres and irradiated with NIR light displayed significantly greater cytotoxic effects than cells incubated with the microspheres alone or cells irradiated with NIR light alone, owing to NIR light-triggered drug release. Treatment of human U87 gliomas and MDA-MB-231 mammary tumor xenografts in nude mice with intratumoral injection of PTX/HAuNS-loaded microspheres followed by NIR irradiation resulted in significant tumor growth delay compared to tumors treated with HAuNS-loaded microspheres (no PTX) and NIR irradiation or with PTX/HAuNS-loaded microspheres alone. Our data support the feasibility of a therapeutic approach in which NIR light is used for simultaneous modulation of drug release and induction of photothermal cell killing.

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Interleukin 17(A) (IL-17) is a potent pro-inflammatory cytokine that acts as a central regulator of inflammatory response within the brain, but its physiological roles under non-inflammatory conditions remain elusive. Here we report that endogenous IL-17 ablates neurogenesis in the adult dentate gyrus (DG) of hippocampus. Genetic deletion of IL-17 increased the number of adult-born neurons in the DG. Further, we found that IL-17 deletion altered cytokine network, facilitated basal excitatory synaptic transmission, enhanced intrinsic neuronal excitability, and increased expression of proneuronal genes in neuronal progenitor cells (NPCs). Our findings suggest a profound role of IL-17 in the negative regulation of adult hippocampal neurogenesis under physiology conditions.