SIG-1451, a Novel, Non-Steroidal Anti-Inflammatory Compound, Attenuates Light-Induced Photoreceptor Degeneration by Affecting the Inflammatory Process.

Age-related macular degeneration is a progressive retinal disease that is associated with factors such as oxidative stress and inflammation. In this study, we evaluated the protective effects of SIG-1451, a non-steroidal anti-inflammatory compound developed for treating atopic dermatitis and known to inhibit Toll-like receptor 4, in light-induced photoreceptor degeneration. SIG-1451 was intraperitoneally injected into rats once per day before exposure to 1000 lx light for 24 h; one day later, optical coherence tomography showed a decrease in retinal thickness, and electroretinogram (ERG) amplitude was also found to have decreased 3 d after light exposure. Moreover, SIG-1451 partially protected against this decrease in retinal thickness and increase in ERG amplitude. One day after light exposure, upregulation of inflammatory response-related genes was observed, and SIG-1451 was found to inhibit this upregulation. Iba-1, a microglial marker, was suppressed in SIG-1451-injected rats. To investigate the molecular mechanism underlying these effects, we used lipopolysaccharide (LPS)-stimulated rat immortalised Müller cells. The upregulation of C-C motif chemokine 2 by LPS stimulation was significantly inhibited by SIG-1451 treatment, and Western blot analysis revealed a decrease in phosphorylated I-κB levels. These results indicate that SIG-1451 indirectly protects photoreceptor cells by attenuating light damage progression, by affecting the inflammatory responses.

Potential Molecular Targets for Treating Neuropathic Orofacial Pain Based on Current Findings in Animal Models.

This review highlights potential molecular targets for treating neuropathic orofacial pain based on current findings in animal models. Preclinical research is currently elucidating the pathophysiology of the disease and identifying the molecular targets for better therapies using animal models that mimic this category of orofacial pain, especially post-traumatic trigeminal neuropathic pain (PTNP) and primary trigeminal neuralgia (PTN). Animal models of PTNP and PTN simulate their etiologies, that is, trauma to the trigeminal nerve branch and compression of the trigeminal root entry zone, respectively. Investigations in these animal models have suggested that biological processes, including inflammation, enhanced neuropeptide-mediated pain signal transmission, axonal ectopic discharges, and enhancement of interactions between neurons and glial cells in the trigeminal pathway, are underlying orofacial pain phenotypes. The molecules associated with biological processes, whose expressions are substantially altered following trigeminal nerve damage or compression of the trigeminal nerve root, are potentially involved in the generation and/or exacerbation of neuropathic orofacial pain and can be potential molecular targets for the discovery of better therapies. Application of therapeutic candidates, which act on the molecular targets and modulate biological processes, attenuates pain-associated behaviors in animal models. Such therapeutic candidates including calcitonin gene-related peptide receptor antagonists that have a reasonable mechanism for ameliorating neuropathic orofacial pain and meet the requirements for safe administration to humans seem worth to be evaluated in clinical trials. Such prospective translation of the efficacy of therapeutic candidates from animal models to human patients would help develop better therapies for neuropathic orofacial pain.

The transcriptome of wild-type and immortalized corneal epithelial cells.

Cellular immortalization enables indefinite expansion of cultured cells. However, the process of cell immortalization sometimes changes the original nature of primary cells. In this study, we performed expression profiling of poly A-tailed RNA from primary and immortalized corneal epithelial cells expressing Simian virus 40 large T antigen (SV40) or the combination of mutant cyclin-dependent kinase 4 (CDK4), cyclin D1, and telomere reverse transcriptase (TERT). Furthermore, we studied the expression profile of SV40 cells cultured in medium with or without serum. The profiling of whole expression pattern revealed that immortalized corneal epithelial cells with SV40 showed a distinct expression pattern from wild-type cells regardless of the presence or absence of serum, while corneal epithelial cells with combinatorial expression showed an expression pattern relatively closer to that of wild-type cells.

[QUANTIFICATION OF CONJUNCTIVAL HYPEREMIA IN RABBITS USING ANALYSIS SOFTWARE].

BACKGROUND/PURPOSE: In a method evaluating conjunctival hyperemia using rabbits, it is common to visually grade the degree of vasodilation. However, this method is limited in evaluating consecutive value and in reproducibility. We quantified the degree of conjunctival hyperemia in rabbits as the area ratio of blood vessels by image analysis, and compared the vascular area percentage calculated by image analysis with the hyperemia score. METHODS: The conjunctiva was photographed before and after the instillation of 0.1% arachidonic acid using a digital medical scope VersaCam® (Nidek Co., Ltd.). Next, the area of the conjunctival blood vessels occupying the area of interest was calculated using hyperemia analysis software. The hyperemia score was visually graded for the degree of conjunctiva vasodilation. Furthermore, the hyperemia score and the vascular area ratio were compared. RESULTS: Fifteen minutes after the instillation of arachidonic acid, the area ratio of the blood vessels in the conjunctiva increased significantly and gradually decreased over time. This trend correlated with the hyperemia score. CONCLUSION: We found that the degree of conjunctival hyperemia in rabbits can be evaluated numerically and quantitatively. This method is considered to be useful for evaluating conjunctival hyperemia in allergic conjunctival diseases.

Geranylgeranyl acetone prevents glutamate-induced cell death in HT-22 cells by increasing mitochondrial membrane potential.

Geranylgeranyl acetone (GGA) protects against various types of cell damages by upregulating heat shock proteins. We investigated whether GGA protects neuronal cells from cell death induced by oxidative stress. Glutamate exposure was lethal to HT-22 cells which comprise a neuronal line derived from mouse hippocampus. This configuration is often used as a model for hippocampus neurodegeneration in vitro. In the present study, GGA protected HT-22 cells from glutamate-induced oxidative stress. GGA pretreatment did not induce heat shock proteins (Hsps). Moreover, reactive oxygen species increased to the same extent in both GGA-pretreated and untreated cells exposed to glutamate. In contrast, glutamate exposure and GGA pretreatment increased mitochondrial membrane potential. However, increases in intracellular Ca2+ concentration were inhibited by GGA pretreatment. In addition, the increase of phosphorylated ERKs by the glutamate exposure was inhibited by GGA pretreatment. These findings suggest that GGA protects HT-22 cells from glutamate-provoked cell death without Hsp induction and that the mitochondrial calcium buffering capacity plays an important role in this protective effect.

Apigenin Regulates Activation of Microglia and Counteracts Retinal Degeneration.

Purpose: Photoreceptor degeneration is a major cause of blindness. Microglia are known to play key roles in the pathogenesis and progression of neural degeneration. We examined the possible use of apigenin, which is a naturally occurring flavonoid, for the treatment of photoreceptor degeneration through regulation of microglial activities. Methods: As in vitro analyses, BV2 and MG5 mouse microglia cell lines were stimulated in the presence or absence of apigenin, and their activation profile was examined. In vivo study was done using rd1 photoreceptor degeneration model, and apigenin was administered by intravitreal injection, and pathological feature was examined. Results: Cell survival was not affected by apigenin in either BV2 and MG5. Apigenin suppressed lipopolysaccharide (LPS)-induced chemokine production in both BV2 and MG5 cells, but phagocytosis was suppressed in MG5 cells but not in BV2 cells. Apigenin inhibited LPS-induced M1 activation but could not drive microglia toward the M2 phenotype. Apigenin suppressed the expression of miR-155 in a dose-dependent manner. Furthermore, the Ets protein level was suppressed by treatment of BV2 cells with apigenin. When rd1 mice were treated with apigenin by intravitreal injection, the expression of inflammatory chemokines in the retina was reduced, and activation of microglia and Müller glia was suppressed. Furthermore, the thickness of the outer nuclear layer of the retina of rd1 mice was thicker in apigenin-treated retinas. Conclusions: Taken together, local administration of apigenin to the retina is a potential therapeutic treatment for photoreceptor degeneration, which involves downregulation of microglia in the retina when photoreceptors are damaged.

Neuroprotective effect of a dietary supplement against glutamate-induced excitotoxicity in retina.

AIM: To evaluate the neuroprotective effect of a dietary supplement (ClearVision EX®; CV) against glutamate-induced excitotoxicity in retina. METHODS: We evaluated the protective effects CV on glutamate-induced cell toxicity of an immortalized mouse hippocampal cell line (HT-22) in vitro and N-methyl-D-aspartate (NMDA) induced retinal injury in vivo. Once-daily oral administration of CV or vehicle (5% Arabic gum) was started the day before the NMDA injection and continued until the end of the study. Electroretinograms (ERGs) were recorded to evaluate the retinal function at 2d after NMDA injection. Furthermore, a histological evaluation, Western blot analysis, and immunohistochemistry were performed for assessing the signal transduction pathway. RESULTS: HT-22 cell death was induced by the addition of glutamate and co-incubation with CV protected against it. Oral administration of CV inhibited the decrease in scotopic threshold response amplitudes induced by the intravitreal injection of NMDA and those of the thickness of the inner retinal layer in the histological evaluation. The increased phosphorylated levels of extracellular signal-regulated kinase (ERK) but not cAMP response element binding protein (CREB) or Akt were observed 1h after NMDA injection in both the vehicle- and CV-treated rats; however, pERK activation was no more upregulated at 3h after NMDA injection. pERK upregulation was observed in Müller cells. CONCLUSION: CV shows a protective effect against both glutamate-induced HT-22 cell death and NMDA-induced retinal damage. pERK upregulation in the Müller cells plays a key role in the protective effect of CV against glutamate-induced retinal toxicity.

Substitution of the N-glycan function in glycosyltransferases by specific amino acids: ST3Gal-V as a model enzyme.

The sialyltranferase ST3Gal-V transfers a sialic acid to lactosylceramide. We investigated the role of each of the N-glycans modifying mouse ST3Gal-V (mST3Gal-V) by measuring the in vitro enzyme activity of Chinese hamster ovary (CHO) cells transfected with ST3Gal-V cDNA or its mutants. By examining mutants of mST3Gal-V, in which each asparagine was replaced with glutamine (N180Q, N224Q, N334Q), we determined that all three sites are N-glycosylated and that each N-glycan is required for enzyme activity. Despite their importance, N-glycosylation sites in ST3Gal-V are not conserved among species. Therefore, we considered whether the function in the activity that is performed in mST3Gal-V by the N-glycan could be substituted for by specific amino acid residues selected from the ST3Gal-V of other species or from related sialyltransferases (ST3Gal-I, -II, -III, and -IV), placed at or near the glycosylation sites. To this end, we constructed a series of interspecies mutants for mST3Gal-V, specifically, mST3Gal-V-H177D-N180S (medaka or tetraodon type), mST3Gal-V-N224K (human type), and mST3Gal-V-T336Q (zebrafish type). The ST3Gal-V activity of these mutants was quite similar to that of the wild-type enzyme. Thus, we have demonstrated here that the N-glycans on mST3Gal-V are required for activity but can be substituted for specific amino acid residues placed at or near the glycosylation sites. We named this method SUNGA (substitution of N-glycan functions in glycosyltransferases by specific amino acids). Furthermore, we verified that the ST3Gal-V mutant created using the SUNGA method maintains its high activity when expressed in Escherichia coli thereby establishing the usefulness of the SUNGA method in exploring the function of N-glycans in vivo.