Narimasa Yoshinaga

B Cell-Derived Vascular Endothelial Growth Factor A Promotes Lymphangiogenesis and High Endothelial Venule Expansion in Lymph Nodes

Vascular endothelial growth factor A (VEGF-A) is a prominent growth factor for both angiogenesis and lymphangiogenesis. Recent studies have shown the importance of VEGF-A in enhancing the growth of lymphatic endothelial cells in lymph nodes (LNs) and the migration of dendritic cells into LNs. VEGF-A is produced in inflamed tissues and/or in draining LNs, where B cells are a possible source of this growth factor. To study the effect of B cell-derived VEGF-A, we created transgenic mice (CD19Cre/hVEGF-Afl) that express human VEGF-A specifically in B cells. We found that the human VEGF-A produced by B cells not only induced lymphangiogenesis in LNs, but also induced the expansion of LNs and the development of high endothelial venules. Contrary to our expectation, we observed a significant decrease in the Ag-specific Ab production postimmunization with OVA and in the proinflammatory cytokine production postinoculation with LPS in these mice. Our findings suggest immunomodulatory effects of VEGF-A: B cell-derived VEGF-A promotes both lymphangiogenesis and angiogenesis within LNs, but then suppresses certain aspects of the ensuing immune responses.

Responsiveness of eyes with polypoidal choroidal vasculopathy with choroidal hyperpermeability to intravitreal ranibizumab

BackgroundTo determine the role played by vascular endothelial growth factor (VEGF) in polypoidal choroidal vasculopathy (PCV) based on an interventional immunology theory.MethodsEyes with PCV were divided in a masked fashion into those with choroidal hyperpermeability (HP group) and those with normal choroidal permeability (NP group) based on the indocyanine green angiograms. The inter-rater agreement rate was evaluated using Fleiss’ kappa. Patients were treated by intravitreal ranibizumab (IVB). The central choroidal thickness and central foveal thickness (CFT) at the baseline and 7 days after the treatment were measured by optical coherence tomography.ResultsAmong the 57 consecutive eyes diagnosed with PCV, 42 eyes of 42 patients met the inclusion criteria (21 eyes/HP group vs 21 eyes /NP group). Central choroidal thickness in HP group was significantly thicker than that in the NP group (P < .001, Mann–Whitney U test). The inter-rater agreement was high with a Fleiss’ kappa = 0.95, P < .0001. The percentage reduction in the CFT in HP group (14.0%) was significantly less than that in NP group (20.4%; P = .013, Mann–Whitney U test).ConclusionsEyes with PCV that are associated with choroidal hyper-permeability may not be strongly associated with VEGF-related pathology, and may not respond favorably to anti-VEGF monotherapy.

NSAIDs inhibit neovascularization of choroid through HO-1-dependent pathway

Intraocular neovascularization is the leading cause of severe visual loss and anti-vascular endothelial growth factor (VEGF) therapy is currently performed for choroidal neovascularization (CNV). Despite its potent anti-angiogenic effect, there are concerns about its long-term safety. Non-steroidal anti-inflammatory drugs (NSAIDs) are common therapeutic agents used for treating inflammatory diseases, and their anti-stress effects are attracting attention now. We studied the effects of topical NSAIDs on CNV, focusing on anti-stress proteins. Cultured retinal pigment epithelium (RPE) cells were treated with NSAIDs: bromfenac, indomethacin, or vehicle control. Transcription factor NF-E2-related factor 2 (Nrf2) and its downstream anti-oxidant protein heme oxygenase (HO)-1 were assessed using western blot and immunohistochemistry. As a result, NSAIDs induced translocation of Nrf2 into the nucleus and the robust expression of HO-1 in a dose- and time-dependent manner. Flow cytometric analysis revealed that bromfenac inhibited H2O2-induced apoptosis in cultured RPE cells. Next, we studied the effects of topical bromfenac on laser-induced CNV model in rat. The expressions of Nrf2 and HO-1, infiltrations of ED-1-positive macrophages at CNV lesions and size were analyzed. VEGF in the ocular fluid of these rats was also measured using enzyme-linked immunosorbent assay. Rats administered an inhibitor of HO-1 stannic mesoporphyrin (SnMP) were also studied. The results showed that topical bromfenac led to translocation of Nrf2 and induction of HO-1 in CNV lesions and that the number of infiltrating macrophages at the CNV lesion decreased. The sizes of CNV lesions were significantly smaller in bromfenac-treated rats than control CNV, and the effects were diminished by SnMP. VEGF increased in the ocular fluid after laser treatment and was inhibited by bromfenac and SnMP canceling these effects. NSAIDs inhibit CNV through the novel anti-stress protein HO-1-dependent pathway, indicating its potential therapeutic value for various intraocular angiogenic diseases including CNV.

Edaravone: a new therapeutic approach for the treatment of acute stroke.

Acute stroke, including acute ischemic stroke (AIS) and acute hemorrhagic stroke, (AHS) is a common medical problem with particular relevance to the demographic changes in industrialized societies. In recent years, treatments for AIS have emerged, including thrombolysis with tissue plasminogen activator (t-PA). Although t-PA is the most effective currently available therapy, it is limited by a narrow therapeutic time window and side effects, and only 3% of all AIS patients receive thrombolysis. Edaravone was originally developed as a potent free radical scavenger and, since 2001, has been widely used to treat AIS in Japan. It was shown that edaravone extended the narrow therapeutic time window of t-PA in rats. The therapeutic time window is very important for the treatment of AIS, and early edaravone treatment is more effective. Thus, more AIS patients might be rescued by administering edaravone with t-PA. Meanwhile, edaravone attenuates AHS-induced brain edema, neurologic deficits and oxidative injury in rats. Although edaravone treatment is currently only indicated for AIS, it does offer neuroprotective effects against AHS in rats. Therefore, we hypothesize that early administration of edaravone can rescue AHS patients as well as AIS patients. Taken together, our findings suggest that edaravone should be immediately administered on suspicion of acute stroke, including AIS and AHS.

Upregulation of non-β cell-derived vascular endothelial growth factor A increases small clusters of insulin-producing cells in the pancreas.

Pancreatic β cell-derived vascular endothelial growth factor A (VEGF-A) contributes to normal β cell function. We therefore hypothesized that non-β cell-derived VEGF-A may affect its properties in adult mice.We generated transgenic mice expressing human VEGF-A (hVEGF-A) in a visceral smooth muscle cell (SMC)-dominant manner under the control of the transgelin (Tagln/SM22α) promoter via a tamoxifen-induced Cre/loxP recombination system (SM-CreER(T2)/hVEGF mice).SM-CreER(T2)/hVEGF mice received tamoxifen orally followed by microscopic examination of their pancreas 4 weeks after the hVEGF-A induction. The number of clusters of insulin-producing cells (IPCs) in islets, pancreatic ducts, and individual IPCs were counted.The number of small IPC clusters (100-215 μm(2)) in the pancreas increased significantly in SM-CreER(T2)/hVEGF mice compared with SM-CreER(T2)(Ki) mice (473 out of 1 992 counts vs. 199 out of 976 counts, p<0.05), although total IPC area and the number of pancreatic duct IPCs, in proportion to exocrine area, were similar between the 2 groups. Although most small IPC clusters observed in SM-CreER(T2)/hVEGF mice were not accompanied by α and/or δ cells, some were attached to a single or a few α cells. An STZ-induced diabetic state in SM-CreER(T2)/hVEGF mice was slightly ameliorated, with only one point of significance 12 weeks after STZ administration, compared with SM-CreER(T2)(Ki) mice.Upregulation of non-β cell-derived VEGF-A may alter the composition of pancreatic IPCs by increasing the number of small IPC clusters. These findings provide new information on the role of non-β cell-derived VEGF-A to IPC regeneration and insulin production.