Zhi-Bin Wang

Tight junction in blood-brain barrier: an overview of structure, regulation, and regulator substances.

Blood‐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.

Propionate Ameliorates Dextran Sodium Sulfate-Induced Colitis by Improving Intestinal Barrier Function and Reducing Inflammation and Oxidative Stress

Propionate is a short chain fatty acid that is abundant as butyrate in the gut and blood. However, propionate has not been studied as extensively as butyrate in the treatment of colitis. The present study was to investigate the effects of sodium propionate on intestinal barrier function, inflammation and oxidative stress in dextran sulfate sodium (DSS)-induced colitis mice. Animals in DSS group received drinking water from 1 to 6 days and DSS [3% (w/v) dissolved in double distilled water] instead of drinking water from 7 to 14 days. Animals in DSS+propionate (DSS+Prop) group were given 1% sodium propionate for 14 consecutive days and supplemented with 3% DSS solution on day 7–14. Intestinal barrier function, proinflammatory factors, oxidative stress, and signal transducer and activator of transcription 3 (STAT3) signaling pathway in the colon were determined. It was found that sodium propionate ameliorated body weight loss, colon-length shortening and colonic damage in colitis mice. Sodium propionate significantly inhibited the increase of FITC-dextran in serum and the decrease of zonula occludens-1 (ZO-1), occludin, and E-cadherin expression in the colonic tissue. It also inhibited the expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) mRNA and phosphorylation of STAT3 in colitis mice markedly, reduced the myeloperoxidase (MPO) level, and increased the superoxide dismutase and catalase level in colon and serum compared with DSS group. Sodium propionate inhibited macrophages with CD68 marker infiltration into the colonic mucosa of colitis mice. These results suggest that oral administration of sodium propionate could ameliorate DSS-induced colitis mainly by improving intestinal barrier function and reducing inflammation and oxidative stress via the STAT3 signaling pathway.

Increasing the Permeability of the Blood-brain Barrier in Three Different Models in vivo.

Blood–brain barrier (BBB) plays significant roles in the circumstance maintains for the central nervous system (CNS). The dysfunction of the BBB could occur in all pathological conditions of CNS diseases, such as ischemic stroke, cerebral edema, or inflammatory disorders. However, the comparisons among different animal models with a broken BBB in vivo are still need to be further studied.

Verification of Motion Sickness Index in Mice

Motion sickness is discomfort felt by individuals caused by repetitive angular and linear acceleration and deceleration [1]. Rodents have been used to model motion sickness, but are of limited value because rodents do not vomit [2,3]. Pica is thought to be the equivalent of vomiting in rats and is widely used to model motion sickness [4]. However, increasing evidence indicated that pica is not a sensitive assay of motion sickness [5]. In a previous study from this laboratory, a set of criteria based on fecal and urinal incontinence was used to quantify the degree of motion sickness induced by horizontal rotation in rats and mice [5]. Whether this set of criteria is suitable to examine the core features of motion sickness (summation, variability, and habituation) is not clear. In this study, we attempted to validate this evaluation criteria in mice with different stimulation patterns, double labyrinthectomized and antimotion sickness drugs. Male mice weighing 18–22 g were purchased from Sino-British SIPPR/BK Lab Animal Ltd (Shanghai, China). All animals received humane care and experimental procedures were in compliance with institutional animal care guidelines. Motion sickness was simulated using a DSL-1 minitype animal centrifuge unit (Peace Medical Equipment Factory, Beijing, China). Symptoms were monitored for a period of 5 min after the rotation. Motion sickness index (MSI) was calculated on the basis of a set of evaluation criteria previously published [5]. Data are expressed as mean ± SD, and analyzed with unpaired Student t-test. Statistical significance was set at P < 0.05. Similar to a previous report [6], we showed that MSI increase was much greater after dual-axis rotation than after single-axis rotation (5.14 ± 1.37 vs. 3.06 ± 1.07, P < 0.05; Figure 1A). MSI was highest with 240◦/s peak speed and 40◦/s2 angular acceleration (Figure 1B). MSI also correlated with the duration of the rotation, and was higher after 40-min rotation than after 10 or 20 min roMotion Sickness Index: Appropriate Evaluation Criteria in Mice tation (Figure 1C). MSI after 60-min rotation was lower than that for 40-min rotation, indicating development of adaption. Alternatively, and the limit of defecation and urination might have been reached. Taken together, these summation observed demonstrated that this method is a suitable criterion for motion sickness. Habituation is a common characteristic of motion sickness. Mitchell et al. showed that kaolin consumption increases initially upon rotation but gradually decreases as the trials progressed [7]. In this study, MSI gradually decreased to a stable level upon daily exposure to rotation over a period of 10–14 days (Figure 1D). The apparent habituation observed in our study support the use of this criteria for motion sickness. The vestibular system is critical in motion sickness. In this study, MSI was decreased by intratympanic injection of gentamycin (2.00 ± 0.98 vs. 4.9 ± 1.48, P < 0.05; Figure 2A). Histological results showed that hair cells and sertoli cells were practically absent in mice receiving gentamycin (Figure 2B). These results demonstrated that similar to the sensitivity of pica to vestibular system damage [8], our criteria is sensitive to bilateral labyrinthectomy. Scopolamine, methylphenidate, diphenhydramine, and nimodipine decreased MSI in mice by 56.7%, 49.8%, 34.0%, and 40.8%, respectively (Figure 2C). The result demonstrated that our evaluation criteria are suitable to evaluated antimotion sickness drugs. However, it is well known that the variability is the other one of the most reliable characteristic of motion sickness. The greater variability of MSI in mice was due to fundamental variability of individual susceptibility to motion sickness per se as well as variability of fecal and urinal incontinence-based evaluation criteria. As a result, animal subjects need to be screened simultaneously under the same condition for drug screening.

Low level of swiprosin-1/EFhd2 in vestibular nuclei of spontaneously hypersensitive motion sickness mice

Susceptibility to motion sickness (MS) varies considerably among humans. However, the cause of such variation is unclear. Here, we used a classical genetic approach to obtain mouse strains highly sensitive and resistant to MS (SMS and RMS). Proteomics analysis revealed substantially lower swiprosin-1 expression in SMS mouse brains. Inducing MS via rotary stimulation decreased swiprosin-1 in the mouse brains. Swiprosin-1 knockout mice were much more sensitive to motion disturbance. Immunohistochemistry revealed strong swiprosin-1 expression in the vestibular nuclei (VN). Over-expressing swiprosin-1 in the VN of SMS mice decreased MS susceptibility. Down-regulating swiprosin-1 in the VN of RMS mice by RNAi increased MS susceptibility. Additional in vivo experiments revealed decreased swiprosin-1 expression by glutamate via the NMDA receptor. Glutamate increased neuronal excitability in SMS or swiprosin-1 knockout mice more prominently than in RMS or wild-type mice. These results indicate that swiprosin-1 in the VN is a critical determinant of the susceptibility to MS.

Swiprosin-1 Promotes Mitochondria-Dependent Apoptosis of Glomerular Podocytes via P38 MAPK Pathway in Early-Stage Diabetic Nephropathy

Background/Aims: Podocyte injury, especially podocyte apoptosis, plays a major role in early-stage diabetic nephropathy (DN). Swiprosin-1, also known as EF hand domain containing 2 (EFhd2), is a Ca2+-binding protein in different cell types. However, the function of swiprosin-1 in podocytes remains unknown. Methods: The expression and distribution of swiprosin-1 were investigated in the mouse renal glomerulus and conditionally immortalized mouse podocyte cell line MPC-5. The expression of swiprosin-1 was also detected in streptozotocin (STZ)-treated mice and MPC-5 cells treated with high glucose (HG). Nephrin and podocin were detected by immunohistochemistry and immunofluroscence. Collagen IV, transforming growth factor-β (TGF-β) and fibronectin mRNA expressions were assayed by real-time PCR. Apoptotic proteins and phosphorylation of p38 mitogen-activated protein kinase (MAPK) were detected by immunoblotting. Results: Swiprosin-1 was found to be expressed in podocytes of the mouse glomerulus and MPC-5 cells. Swiprosin-1 expression was increased in STZ-treated mice and MPC-5 cells treated with HG. In Swiprosin-1-/- diabetic mice, kidney/ body weight, urinary albumin, podocyte foot process effacement and glomerular basement membrane thickening were attenuated; the downregulation of nephrin and podocin expression in the glomerulus was inhibited; and the upregulation of collagen IV, TGF-β and fibronectin mRNA expression in the renal cortex was ameliorated as compared with those in diabetic swiprosin-1+/+ mice. In addition, the increased apoptosis of podocytes, proapoptotic protein expression and p38 phosphorylation in Swiprosin-1-/- diabetic mice were inhibited as compared with those in diabetic swiprosin-1+/+ mice. Knockdown of swiprosin-1 in MPC-5 cells reduced the apoptosis of podocytes, proapoptotic protein expression and p38 phosphorylation induced by HG. Targeted knockdown of p38 attenuated the increased apoptosis of MPC-5 cells over-expressing swiprosin-1. Conclusion: Swiprosin-1 expression in podocytes of the mouse glomerulus played a critical role in early-stage DN. Swiprosin-1 deficiency in early DN attenuated mitochondria-dependent podocyte apoptosis induced by hyperglycemia or HG via p38 MAPK signaling pathway.

Oxidative stress is not involved in motion sickness in mice.

Some indirect evidences indicate a possible correlation between oxidative stress and motion sickness. The aim of this research was to investigate whether oxidative stress contributing to motion sickness in mice or not.

Swiprosin-1 deficiency impairs macrophage immune response of septic mice

Despite the fact that many therapeutic strategies have been adopted to delay the development of sepsis, sepsis remains one of the leading causes of death in noncoronary intensive care units. Recently, sepsis-3 was defined as life-threatening organ dysfunction due to a dysregulated host response to infection. Here, we report that swiprosin-1 (also known as EFhd2) plays an important role in the macrophage immune response to LPS-induced or cecal ligation and puncture-induced (CLP-induced) sepsis in mice. Swiprosin-1 depletion causes higher mortality, more severe organ dysfunction, restrained macrophage recruitment in the lung and kidney, and attenuated inflammatory cytokine production (including IL-1β, IL-6, TNF-α, IL-10, and IFN-γ). The immunosuppression caused by swiprosin-1 deficiency is manifested by impaired bactericidal capacity and decreased HLA-DR expression in macrophages. Swiprosin-1 affects the activation of the JAK2/STAT1/STAT3 pathway by regulating the expression of IFN-γ receptors in macrophages. Our findings provide a potential target for the regulation of the macrophage immune response in sepsis.

Motion sickness induces intestinal transit increase in mice.

Motion sickness in rodents could be induced with vestibular stimulation from rotation [1]. However, rats and mice could not nauseate and vomit due to the powerful barrier between the stomach and the esophagus [2]. Instead, they exhibit pica behavior (eating of kaolin), which has already been thought as an alternative to nausea and vomiting in rats [3]. Nonetheless, no significant increase in kaolin consumption after rotation was observed in mice [4,5]. We speculated that the amount of kaolin consumption induced by rotation is too little to distinguish from that due to the curious habit in mice. Furthermore, the biological basis of pica induced by motion sickness in rodents is still unknown. Recently, motion sickness index (MSI), fecal-based evaluation criteria, was verified to be suitable for evaluating the severity of motion sickness in mice [4,6]. The results indicated that intestinal transit may increase when mice suffer from motion sickness. On the other hand, it was demonstrated that space motion sickness could result in gastric stasis in astronauts [7]. How to clarify this conflict? We presume that the gastric stasis does exist in mice after rotary stimulus, and then, the intestinal transit is increased to resist gastric stasis instead of emesis. Moreover, in our previous study, we found that fecal granules determined MSI score to a great extent. Therefore, there may be a correlation between intestinal transit and MSI. The present work was therefore designed to investigate intestinal transit variation during motion sickness and the correlation between intestinal transit and MSI in mice. C57BL/6J male mice weighing 18–22 g were purchased from SLRC Laboratory Animal Ltd (Shanghai, China). All animals received humane care, and experimental procedures were in compliance with institutional animal care guidelines. Motion sickness was induced by biaxial rotary stimulus with 360°/s peak velocity and 20°/s angular accelerative rotation for 40 min. MSI was calculated on the basis of a set of evaluation criteria previously published [4]. Kaolin consumption in 24 h prerotation or postrotation was recorded. Small intestinal transit and colonic transit activity were determined using 10% wood charcoal mixing 5% gum arabic as tracer dye. The ratio of distance from pylorus to the end of tracer dye and distance from pylorus to cecum was identified as small intestinal transit activity. The ratio of distance from ileocecal junction to the end of tracer dye to total length of colon was identified as colonic transit activity [8]. Data are expressed as mean SD. Comparisons of parameters among two groups were made by the unpaired Student’s t-test. Data involving more than two groups were assessed by analysis of variance (ANOVA). Statistical significance was set at P < 0.05. Liu et al. [9] reported mice ate a small amount of kaolin in normal condition (<0.2 g each day). In our experiment, kaolin consumption before and after rotary stimulus was 0.35 0.61 and 0.38 0.54 g in 24 h, respectively. Moreover, among 42 mice, 57.1% showed increased kaolin consumption after rotary stimulus. Inversely, 42.9% exhibited decreased kaolin consumption. Taken together, the results indicated that the basic consumption of kaolin is little, and the variability of kaolin consumption is huge in mice. Our results showed that pica is not suitable to evaluate the severity of motion sickness in mice. In normal condition, the intestinal transit was increased with time after intragastric administration of tracer dye (data not

EFhd2/swiprosin-1 regulates LPS-induced macrophage recruitment via enhancing actin polymerization and cell migration

ABSTRACT Macrophage motility is vital in innate immunity, which contributes strategically to the defensive inflammation process. During bacterial infection, lipopolysaccharide (LPS) potently activates the migration of macrophages via the NF‐&kgr;B/iNOS/c‐Src signaling pathway. However, the downstream region of c‐Src that participates in macrophage migration is unclear. EFhd2, a novel actin bundling protein, was evaluated for its role in LPS‐stimulated macrophage migration in this study. We found that LPS stimulated the up‐regulation, tyrosine phosphorylation and membrane translocation of EFhd2 in macrophages. The absence of EFhd2 inhibited the recruitment of macrophages in the lungs of LPS‐induced septic mice. LPS‐induced macrophage migration was neutralized by the deletion of EFhd2. EFhd2‐mediated up‐regulation of NFPs (including Rac1/Cdc42, N‐WASP/WAVE2 and Arp2/3 complex) induced by LPS could be used to explain the role of EFhd2 in promoting actin polymerization. Furthermore, the purified EFhd2 could directly promote actin polymerization in vitro. Dasatinib, a c‐Src specific inhibitor, inhibited the up‐regulation of EFhd2 stimulated by LPS. Therefore, our study demonstrated that EFhd2 might be involved in LPS‐stimulated macrophage migration, which provides a potential target for LPS‐activated c‐Src during macrophage mobilization. HighlightsEFhd2 is involved in LPS‐induced migration of macrophage.EFhd2 promotes actin polymerization via enhancing the expression of NPFs.The up‐regulation of EFhd2 induced by LPS depends on the activity of c‐Src.