In vivo fluorescence microscopy of corneal neovascularization

Clematichinenoside protects blood brain barrier against ischemic stroke superimposed on systemic inflammatory challenges through up-regulating A20

Suppression of excessive inflammation can ameliorate blood brain barrier (BBB) injury, which shows therapeutic potential for clinical treatment of brain injury induced by stroke superimposed on systemic inflammatory diseases. In this study, we investigated whether and how clematichinenoside (AR), an anti-inflammatory triterpene saponin, protects brain injury from stroke superimposed on systemic inflammation. Lipopolysaccharide (LPS) was intraperitoneally injected immediately after middle cerebral artery occlusion (MCAO) in rats. Rat microvessel endothelial cells (rBMECs) were exposed to hypoxia/reoxygenation (H/R) coexisting with LPS. The results revealed that AR suppressed the excessive inflammation, restored BBB dysfunction, alleviated brain edema, decreased neutrophil infiltration, lessened neurological dysfunction, and decreased infarct rate. Further study demonstrated that the expression of nucleus nuclear factor kappa B (NF-κB), inducible nitric oxide synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α) and interlukin-1β (IL-1β) were suppressed by AR via zinc finger protein A20. Besides, AR increased in vitro BBB integrity through A20. In conclusion, AR alleviated cerebral inflammatory injury through A20-NF-κB signal pathway, offering an alternative medication for stroke associated with systemic inflammatory diseases.

Analysis of cardiomyocyte movement in the developing murine heart

The precise assemblage of several types of cardiac precursors controls heart organogenesis. The cardiac precursors show dynamic movement during early development and then form the complicated heart structure. However, cardiomyocyte movements inside the newly organized mammalian heart remain unclear. We previously established the method of ex vivo time-lapse imaging of the murine heart to study cardiomyocyte behavior by using the Fucci (fluorescent ubiquitination-based cell cycle indicator) system, which can effectively label individual G1, S/G2/M, and G1/S-transition phase nuclei in living cardiomyocytes as red, green, and yellow, respectively. Global analysis of gene expression in Fucci green positive ventricular cardiomyocytes confirmed that cell cycle regulatory genes expressed in G1/S, S, G2/M, and M phase transitions were upregulated. Interestingly, pathway analysis revealed that many genes related to the cell cycle were significantly upregulated in the Fucci green positive ventricular cardiomyocytes, while only a small number of genes related to cell motility were upregulated. Time-lapse imaging showed that murine proliferating cardiomyocytes did not exhibit dynamic movement inside the heart, but stayed on site after entering the cell cycle.

The expression of nuclear factor kappa B in inflammation-induced rat corneal neovascularization

PURPOSE

To investigate the involvement of the nuclear-transfactor-kappa B (NF-kappa B) in the rat model of inflammation-induced corneal neovascularization (CNV).

METHODS

The CNV model in Sprague-Dawley rats was induced by alkaline cauterization of the central cornea. The corneas were examined by a slit lamp microscope. NF-kappa B was assayed by Western blot. Vascular endothelial growth factor (VEGF) protein was evaluated by immunohistochemistry. VEGF mRNA levels were determined by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Morphologically, the CNV was shown on the second day after cautery. In corneas after cautery, NF-kappa B protein increased 6 hours after cautery, peaked 4 days after cautery, and decreased to near baseline by day 14. VEGF protein and mRNA increased gradually in the early stage after cautery, reached the highest level on the fourth day, and then decreased to near baseline slowly after 7 days.

CONCLUSIONS

The activated NF-kappa B was up-regulated in the early stage of CNV of rat induced by cauterization, which suggests it may participate in the pathogenesis of wound healing, inflammation, and neovascularization processes in the cornea.

Selective uptake of indocyanine green by reticulocytes in circulation

PURPOSE

Hyperfluorescent cells labeled with indocyanine green (ICG) have been observed in retinal and choroidal circulation using scanning laser ophthalmoscopy. It has been suggested that ICG labels leukocytes and that ICG can be used to track leukocyte movement in vivo. The purpose of this study is to identify the cell population that takes up ICG and to study their trafficking pattern in vivo by confocal fluorescence microscopy.

METHODS

ICG was injected into the mouse tail vein, and images were taken by in vivo confocal microscopy. The trafficking pattern of ICG-labeled cells was compared with that of rhodamine 6G-labeled leukocytes. In vitro labeling of human blood cells with antibodies against cell lineage markers and with DNA stains was further used to identify the ICG-labeled cells. Antibodies against the following cell surface markers were used: CD45 (leukocytes), CD3 (T lymphocytes), CD19 (B lymphocytes), CD16 (Fc receptor), glycophorin A (erythroid lineage cells), and CD71 (transferrin receptor).

RESULTS

The ICG-labeled cells were made up of two blood cell populations with distinct levels of ICG uptake. The strongly ICG-labeled cells did not roll on dermal vascular endothelium in vivo, in contrast to rhodamine 6G-labeled leukocytes. They were identified as reticulocytes because antibody staining showed that they were CD 45(-), glycophorin A(+) and CD 71(+). The weakly ICG-labeled cells were identified as neutrophils because they were CD45(+), CD16(+), CD3(-), and CD19(-).

CONCLUSIONS

ICG strongly labels reticulocytes and weakly labels neutrophils. To the authors' knowledge, this is the first report of selective staining of reticulocytes by ICG.

Immunohistochemical localization of vascular endothelial growth factor, transforming growth factor alpha, and transforming growth factor beta1 in human corneas with neovascularization

PURPOSE

To analyze presence and distribution of vascular endothelial growth factor (VEGF), transforming growth factor (TGF)alpha, and TGFbeta1 in human corneas with neovascularization due to different corneal diseases.

METHODS

Indirect immunohistochemistry for VEGF, TGFalpha, and TGFbeta1, was performed on paraffin-embedded corneas obtained by keratoplasty. Corneas from each of the four main groups of histopathologic diagnoses associated with corneal neovascularization were analyzed (scarring after keratitis, graft rejection/insufficiency, acute necrotizing keratitis, scarring after mechanical/chemical injury). Subclassification of inflammatory infiltrates was done using immunohistochemistry for CD3 (T-lymphocytes) and CD68 (macrophages).

RESULTS

The analyzed angiogenic factors were detectable in corneas from all four histopathologic groups in a similar distribution; capillary endothelial cells, stromal and intravascular inflammatory cells (T-lymphocytes, macrophages), and basal corneal epithelial cells stained positive for the tested angiogenic factors.

CONCLUSION

The angiogenic factors VEGF, TGFalpha, and TGFbeta1 are detectable in human corneas with neovascularization. Their distribution is quite uniform in different corneal diseases, resulting in corneal angiogenesis. An antiangiogenic therapy inhibiting corneal neovascularization by antagonizing angiogenic factors would have to counteract several angiogenic factors.

Digital video-imaging of leukocyte migration in the iris: intravital microscopy in a physiological model during the onset of endotoxin-induced uveitis

The process of inflammation is accompanied by an alteration of leukocyte-endothelial dynamics. Reciprocal changes in the endothelium and the white cell permit the leukocyte to relinquish its normal free-flowing state in order to roll, arrest, and emigrate through the endothelium. Although intravital microscopy is an established method to observe this process, the eye has been under-utilized for this purpose. Iris vasculature can be videophotographed without the artifact of trauma. We used rhodamine 6G in vivo staining of leukocytes from BALB/c mice in a model of inflammation induced by intravitreally injected endotoxin. Digital video technology was used to record observations at baseline, 2 h, and 4 h after the endotoxin injection. Off-line analysis of microhemodynamic parameters established that the percentage of venules exhibiting rolling increased significantly from 4% at baseline to 34% at 2 h and 82% at 4 h after endotoxin injection. We found a marked increase in leukocyte arrest within 4 h (601+/-119 cells per mm(2) vs. 2+/-1 cells per mm(2) in control animals). Although shear stress differs minimally between iris arterioles and venules, both rolling and arrest occurred preferentially in venules indicating that shear stress is not the dominant factor for determining cell adhesion. Compared to previous reports on intravital microscopy, our methodology includes refinements or advantages in visualizing cells that have transmigrated as well as the avoidance of surgical trauma. The resolution and quantifiable nature of this technique are such that the methodology can be applied to repetitive observation of leukocyte-endothelial dynamics during an immune response.