Disorders characterized by ischemia/reperfusion (I/R), such as myocardial infarction, stroke, and peripheral vascular disease, continue to be among the most frequent causes of debilitating disease and death. Tissue injury and/or death occur as a result of the initial ischemic insult, which is determined primarily by the magnitude and duration of the interruption in the blood supply, and then subsequent damage induced by reperfusion. During prolonged ischemia, ATP levels and intracellular pH decrease as a result of anaerobic metabolism and lactate accumulation. As a consequence, ATPase-dependent ion transport mechanisms become dysfunctional, contributing to increased intracellular and mitochondrial calcium levels (calcium overload), cell swelling and rupture, and cell death by necrotic, necroptotic, apoptotic, and autophagic mechanisms. Although oxygen levels are restored upon reperfusion, a surge in the generation of reactive oxygen species occurs and proinflammatory neutrophils infiltrate ischemic tissues to exacerbate ischemic injury. The pathologic events induced by I/R orchestrate the opening of the mitochondrial permeability transition pore, which appears to represent a common end-effector of the pathologic events initiated by I/R. The aim of this treatise is to provide a comprehensive review of the mechanisms underlying the development of I/R injury, from which it should be apparent that a combination of molecular and cellular approaches targeting multiple pathologic processes to limit the extent of I/R injury must be adopted to enhance resistance to cell death and increase regenerative capacity in order to effect long-lasting repair of ischemic tissues.

/pdf/cell-biology-of-ischemia-reperfusion-injury-1rdtb8k8os.pdf

Cell Biology of Ischemia/Reperfusion Injury

Cannabis sativa is the source of a unique set of compounds known collectively as plant cannabinoids or phytocannabinoids. This review focuses on the manner with which three of these compounds, (-)-trans-delta9-tetrahydrocannabinol (delta9-THC), (-)-cannabidiol (CBD) and (-)-trans-delta9-tetrahydrocannabivarin (delta9-THCV), interact with cannabinoid CB1 and CB2 receptors. Delta9-THC, the main psychotropic constituent of cannabis, is a CB1 and CB2 receptor partial agonist and in line with classical pharmacology, the responses it elicits appear to be strongly influenced both by the expression level and signalling efficiency of cannabinoid receptors and by ongoing endogenous cannabinoid release. CBD displays unexpectedly high potency as an antagonist of CB1/CB2 receptor agonists in CB1- and CB2-expressing cells or tissues, the manner with which it interacts with CB2 receptors providing a possible explanation for its ability to inhibit evoked immune cell migration. Delta9-THCV behaves as a potent CB2 receptor partial agonist in vitro. In contrast, it antagonizes cannabinoid receptor agonists in CB1-expressing tissues. This it does with relatively high potency and in a manner that is both tissue and ligand dependent. Delta9-THCV also interacts with CB1 receptors when administered in vivo, behaving either as a CB1 antagonist or, at higher doses, as a CB1 receptor agonist. Brief mention is also made in this review, first of the production by delta9-THC of pharmacodynamic tolerance, second of current knowledge about the extent to which delta9-THC, CBD and delta9-THCV interact with pharmacological targets other than CB1 or CB2 receptors, and third of actual and potential therapeutic applications for each of these cannabinoids.

https://bpspubs.onlinelibrary.wiley.com/doi/pdf/10.1038/sj.bjp.0707442

The diverse CB1 and CB2 receptor pharmacology of three plant cannabinoids: Δ9-tetrahydrocannabinol, cannabidiol and Δ9-tetrahydrocannabivarin

A Novel Nanoparticle Drug Delivery System: The Anti-inflammatory Activity of Curcumin Is Enhanced When Encapsulated in Exosomes

Single-Cell RNA Sequencing of Microglia throughout the Mouse Lifespan and in the Injured Brain Reveals Complex Cell-State Changes.

Keywords: Photomedicine group Reference LPAS-ARTICLE-1998-003View record in Web of Science Record created on 2007-07-20, modified on 2016-08-08

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1751-1097.1998.tb02521.x

In Vivo Fluorescence Spectroscopy and Imaging for Oncological Applications

PURPOSE. Nitric oxide (NO) is involved in leukostasis and bloodretinal barrier (BRB) breakdown in the early stages of diabetic retinopathy (DR), but it is unclear which NO synthase (NOS) isoforms are primarily involved. In this study, the authors aimed to clarify the involvement of constitutive (eNOS, nNOS) and inducible NOS (iNOS) isoforms and the mechanisms underlying NO-mediated leukostasis and BRB breakdown. METHODS. Diabetes was induced with streptozotocin for 2 weeks. Mice were treated with a NOS inhibitor, N G -nitro-Larginine methyl ester (L-NAME), which shows a preference for constitutive isoforms over iNOS. Vessel leakage was assessed with Evans blue. Leukostasis was quantified in flat-mounted retinas with confocal microscopy, in vivo with a scanning laser ophthalmoscope, and in vitro in a retinal endothelial cell line. ICAM-1, occludin, and ZO-1 levels were assessed by Western blot, flow cytometry, or immunohistochemistry. Nitrotyrosine content was assessed by immunohistochemistry. RESULTS. Diabetes increased leukostasis within retinal vessels and BRB permeability, which were reduced by L-NAME. Similar effects were observed in diabetic iNOS knockout mice. In diabetic mouse retinas, ICAM-1 protein levels increased, whereas the immunoreactivity of tight junction proteins, occludin and ZO-1 decreased, in correlation with increased protein levels of all NOS isoforms. Those effects were prevented by L-NAME and also in diabetic iNOS knockout mice. High glucose and nitrosative/oxidative stress also increased leukostasis caused by ICAM-1 upregulation. CONCLUSIONS. These results indicate that the iNOS isoform plays a predominant role in leukostasis and BRB breakdown. The mechanism involves ICAM-1 upregulation and tight junction protein downregulation. (Invest Ophthalmol Vis Sci. 2007;48: 5257‐5265) DOI:10.1167/iovs.07-0112

/pdf/inducible-nitric-oxide-synthase-isoform-is-a-key-mediator-of-2en8h06jpe.pdf

Inducible nitric oxide synthase isoform is a key mediator of leukostasis and blood-retinal barrier breakdown in diabetic retinopathy.

Summary Fundus autofluorescence (AF) imaging by confocal scanning laser ophthalmoscopy has been widely used by ophthalmologists in the diagnosis/monitoring of various retinal disorders. It is believed that fundus AF is derived from lipofuscin in retinal pigment epithelial (RPE) cells; however, direct clinicopathological correlation has not been possible in humans. We examined fundus AF by confocal scanning laser ophthalmoscopy and confocal microscopy in normal C57BL/6 mice of different ages. Increasingly strong AF signals were observed with age in the neuroretina and subretinal/RPE layer by confocal scanning laser ophthalmoscopy. Unlike fundus AF detected in normal human subjects, mouse fundus AF appeared as discrete foci distributed throughout the retina. Most of the AF signals in the neuroretina were distributed around retinal vessels. Confocal microscopy of retinal and choroid/ RPE flat mounts demonstrated that most of the AF signals were derived from Iba-1 + perivascular and subretinal microglia. An age-dependent accumulation of Iba-1 + microglia at the subretinal space was observed. Lipofuscin granules were detected in large numbers in subretinal microglia by electron microscopy. The number of AF + microglia and the amount of AF granules/cell increased with age. AF granules/lipofuscin were also observed in RPE cells in mice older than 12 months, but the number of AF + RPE cells was very low (1.48 mm –2 and 5.02 mm –2 for 12 and 24 months, respectively) compared to the number of AF + microglial cells (20.63 mm –2 and 76.36 mm –2 for 6 and 24 months, respectively). The fluorescence emission fingerprints of AF granules in subretinal microglia were the same as those in RPE cells. Our observation suggests that perivascular and subretinal microglia are the main cells producing lipofuscin in normal aged mouse retina and are responsible for in vivo fundus AF. Microglia may play an important role in retinal aging and age-related retinal diseases.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-9726.2007.00351.x

Age-dependent accumulation of lipofuscin in perivascular and subretinal microglia in experimental mice.

Ultra-Wide-Field Fluorescein Angiography of the Ocular Fundus

Previous studies have shown that cannabinoids have anti-inflammatory and immune-modulating effects, but the precise mechanisms of action remain to be elucidated. In this study, we investigated the effect of JWH 133, a selective agonist for cannabinoid receptor 2, the main receptor expressed on immune cells, in a model of autoimmune disease, experimental autoimmune uveoretinitis (EAU). JWH 133 suppressed EAU in a dose-dependent manner (0.015-15 mg/kg), and the suppressive effect could be achieved in the disease-induction stage and the effector stage. Leukocytes from mice, which had been treated with JWH 133, had diminished responses to retinal peptide and mitogen Con A stimulation in vitro. In vivo JWH 133 treatment also abrogated leukocyte cytokine/chemokine production. Further in vitro studies indicated that JWH 133 down-regulated the TLR4 via Myd88 signal transduction, which may be responsible for its moderate, suppressive effect on antigen presentation. In vivo JWH 133 treatment (1 mg/kg) also suppressed leukocyte trafficking (rolling and infiltration) in inflamed retina as a result of an effect on reducing adhesion molecules CD162 (P-selectin glycoprotein ligand 1) and CD11a (LFA-1) expression on T cells. In conclusion, the cannabinoid agonist JWH 133 has a high in vivo, anti-inflammatory property and may exert its effect via inhibiting the activation and function of autoreactive T cells and preventing leukocyte trafficking into the inflamed tissue.

https://jlb.onlinelibrary.wiley.com/doi/epdf/10.1189/jlb.0307159

Anti-inflammatory property of the cannabinoid receptor-2-selective agonist JWH-133 in a rodent model of autoimmune uveoretinitis.

The scanning laser ophthalmoscope (SLO) offers the potential for retinal imaging that is complementary both to that of the fundus camera and also the newly developing technique of optical coherence tomography (OCT) It has the ability to produce rapid images at low light levels using light of specific wavelengths This permits temporal studies of fluorescent-labelled cells which offer a unique insight into inflammatory processes in the eye The facility to image with several different wavelengths simultaneously offers the potential for spectral imaging of retinal tissue with the aim of revealing those early changes in tissue perfusion that indicate the onset of retinal disease, so increasing the probability of successful therapy

Ayyakkannu Manivannan

Papers

Inducible nitric oxide synthase isoform is a key mediator of leukostasis and blood-retinal barrier breakdown in diabetic retinopathy.

Age-dependent accumulation of lipofuscin in perivascular and subretinal microglia in experimental mice.

Ultra-Wide-Field Fluorescein Angiography of the Ocular Fundus

Anti-inflammatory property of the cannabinoid receptor-2-selective agonist JWH-133 in a rodent model of autoimmune uveoretinitis.

The scanning laser ophthalmoscope--a review of its role in bioscience and medicine.