Sandeep Gopalakrishnan

Amelioration of Experimental Autoimmune Encephalomyelitis in C57BL/6 Mice by Photobiomodulation Induced by 670 nm Light

Background The approved immunomodulatory agents for the treatment of multiple sclerosis (MS) are only partially effective. It is thought that the combination of immunomodulatory and neuroprotective strategies is necessary to prevent or reverse disease progression. Irradiation with far red/near infrared light, termed photobiomodulation, is a therapeutic approach for inflammatory and neurodegenerative diseases. Data suggests that near-infrared light functions through neuroprotective and anti-inflammatory mechanisms. We sought to investigate the clinical effect of photobiomodulation in the Experimental Autoimmune Encephalomyelitis (EAE) model of multiple sclerosis. Methodology/Principal Findings The clinical effect of photobiomodulation induced by 670 nm light was investigated in the C57BL/6 mouse model of EAE. Disease was induced with myelin oligodendrocyte glycoprotein (MOG) according to standard laboratory protocol. Mice received 670 nm light or no light treatment (sham) administered as suppression and treatment protocols. 670 nm light reduced disease severity with both protocols compared to sham treated mice. Disease amelioration was associated with down-regulation of proinflammatory cytokines (interferon-γ, tumor necrosis factor-α) and up-regulation of anti-inflammatory cytokines (IL-4, IL-10) in vitro and in vivo. Conclusion/Significance These studies document the therapeutic potential of photobiomodulation with 670 nm light in the EAE model, in part through modulation of the immune response.

Optical imaging of mitochondrial redox state in rodent model of retinitis pigmentosa

Abstract. Oxidative stress (OS) and mitochondrial dysfunction contribute to photoreceptor cell loss in retinal degenerative disorders. The metabolic state of the retina in a rodent model of retinitis pigmentosa (RP) was investigated using a cryo-fluorescence imaging technique. The mitochondrial metabolic coenzymes nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are autofluorescent and can be monitored without exogenous labels using optical techniques. The cryo-fluorescence redox imaging technique provides a quantitative assessment of the metabolism. More specifically, the ratio of the fluorescence intensity of these fluorophores (NADH/FAD), the NADH redox ratio (RR), is a marker of the metabolic state of the tissue. The NADH RR and retinal function were examined in an established rodent model of RP, the P23H rat compared to that of nondystrophic Sprague-Dawley (SD) rats. The NADH RR mean values were 1.11±0.03 in the SD normal and 0.841±0.01 in the P23H retina, indicating increased OS in the P23H retina. Electroretinographic data revealed a significant reduction in photoreceptor function in P23H animals compared to SD nozrmal rats. Thus, cryo-fluorescence redox imaging was used as a quantitative marker of OS in eyes from transgenic rats and demonstrated that alterations in the oxidative state of eyes occur during the early stages of RP.

Photobiomodulation Induced by 670 nm Light Ameliorates MOG35-55 Induced EAE in Female C57BL/6 Mice: A Role for Remediation of Nitrosative Stress

Background Experimental autoimmune encephalomyelitis (EAE) is the most commonly studied animal model of multiple sclerosis (MS), a chronic autoimmune demyelinating disorder of the central nervous system. Immunomodulatory and immunosuppressive therapies currently approved for the treatment of MS slow disease progression, but do not prevent it. A growing body of evidence suggests additional mechanisms contribute to disease progression. We previously demonstrated the amelioration of myelin oligodendrocyte glycoprotein (MOG)-induced EAE in C57BL/6 mice by 670 nm light-induced photobiomodulation, mediated in part by immune modulation. Numerous other studies demonstrate that near-infrared/far red light is therapeutically active through modulation of nitrosoxidative stress. As nitric oxide has been reported to play diverse roles in EAE/MS, and recent studies suggest that axonal loss and progression of disability in MS is mediated by nitrosoxidative stress, we investigated the effect of 670 nm light treatment on nitrosative stress in MOG-induced EAE. Methodology Cell culture experiments demonstrated that 670 nm light-mediated photobiomodulation attenuated antigen-specific nitric oxide production by heterogenous lymphocyte populations isolated from MOG immunized mice. Experiments in the EAE model demonstrated down-regulation of inducible nitric oxide synthase (iNOS) gene expression in the spinal cords of mice with EAE over the course of disease, compared to sham treated animals. Animals receiving 670 nm light treatment also exhibited up-regulation of the Bcl-2 anti-apoptosis gene, an increased Bcl-2:Bax ratio, and reduced apoptosis within the spinal cord of animals over the course of disease. 670 nm light therapy failed to ameliorate MOG-induced EAE in mice deficient in iNOS, confirming a role for remediation of nitrosative stress in the amelioration of MOG-induced EAE by 670 nm mediated photobiomodulation. Conclusions These data indicate that 670 nm light therapy protects against nitrosative stress and apoptosis within the central nervous system, contributing to the clinical effect of 670 nm light therapy previously noted in the EAE model.

Endogenous Events Modulating Myogenic Regulation of Cerebrovascular Function

The existence of arterial myogenic tone was first described by Bayliss in 1902, however, its association with pressure-dependent membrane depolarization was not observed until 1984. The factors that mediate myogenic arterial constriction remain unknown. One possible clue was a finding by our laboratory that cerebral arterial muscle cells express CYP 4A ω-hydroxylase enzyme that catalyzes the formation of the potent vasoconstrictor 20-hydroxyeicosatetraenoic acid (20-HETE) from arachidonic acid (AA), the production of which increased by elevations of intravascular pressure. 20-HETE activates protein kinase C (PKC), inhibits Ca(2+)-activated K(+) (KCa) channels, depolarizes arterial muscle cell membrane, activates L-type Ca(2+) channels, increases intracellular Ca(2+) ([Ca(2+)]i) and mediates autoregulation of cerebral blood flow. Emerging evidence indicates that 20-HETE level increases in ischemia/reperfusion injury and stimulates production of reactive oxygen species (ROS) resulting in oxidative stress induced ischemic stroke injury, which can be prevented by inhibition of 20-HETE synthesis or action. The brain also expresses CYP epoxygenases that convert AA to the vasodilator epoxyeicosatrienoic acids (EETs), the production of which increases in ischemia and provide protection against ischemia-induced tissue damage. Basal or stimulus released ROS act to modify cerebral myogenic tone. Similar to other enzymes CYP epoxygenase and ω-hydroxylase also generate ROS that modify myogenic cerebral reactivity. Hypoxia per se or adenosine released during hypoxia induces increased production of ROS that alter cerebrovascular function. The capacity of the brain to express CYP enzymes that produce bioactive EETs and 20-HETE and generate ROS has a significant bearing in regulating the dynamics of cerebral blood flow and serve as potential therapeutic targets for the management of pathologic disorders of the cerebral circulation.

Photobiomodulation reduces photoreceptor death and regulates cytoprotection in early states of P23H retinal dystrophy

Irradiation by light in the far-red to near-infrared (NIR) region of the spectrum (photobiomodulation, PBM) has been demonstrated to attenuate the severity of neurodegenerative disease in experimental and clinical studies. The purpose of this study was to test the hypothesis that 670 nm PBM would protect against the loss of retinal function and improve photoreceptor survival in a rodent model of retinitis pigmentosa, the P23H transgenic rat. P23H rat pups were treated once per day with a 670 nm LED array (180 sec treatments at 50 mW/cm2; fluence 9 joules/cm2) (Quantum Devices Inc., Barneveld WI) from postnatal day (p) 16-20 or from p10-20. Sham-treated rats were restrained, but not exposed to NIR light. The status of the retina was determined at p22 by assessment of mitochondrial function, oxidative stress and cell death. In a second series of studies, retinal status was assessed at p30 by measuring photoreceptor function by ERG and retinal morphology by Spectral Domain Optical Coherence Tomography (SD-OCT). 670 nm PBM increased retinal mitochondrial cytochrome oxidase activity and upregulated the retina’s production of the key mitochondrial antioxidant enzyme, MnSOD. PBM also attenuated photoreceptor cell loss and improved photoreceptor function. PBM protects photoreceptors in the developing P23H retina, by augmenting mitochondrial function and stimulating antioxidant protective pathways. Photobiomodulation may have therapeutic potential, where mitochondrial damage is a step in the death of photoreceptors.

Feasibility and Pilot Testing of a Mindfulness Intervention for Frail Older Adults and Individuals With Dementia

Mindfulness interventions have been beneficial for healthy adults and individuals experiencing a stressful medical or mental health diagnosis. The purposes of the current study were to: (a) determine feasibility of mindfulness for older adults in long-term residential settings, and (b) examine differences in outcomes between a mindfulness and cognitive activity. The current study is the first mindfulness study to include individuals in moderate and severe stages of dementia, and included 36 individuals with a range of cognitive abilities. A crossover design was used, and the intervention was feasible for continued practice by individuals with cognitive impairment. Statistically significant short-term changes in agitation, discomfort, anger, and anxiety were found. Nighttime sleep did not improve, but participants slept less during the day. Long-term changes in outcomes were not found. Mindfulness may be useful in decreasing emotional reactivity and improving well-being of older adults in long-term care. TARGETS Individuals with multiple chronic conditions, including cognitive impairment. INTERVENTION DESCRIPTION The Present in the Now (PIN) intervention is a mindfulness intervention with three components: attentional skill exercises, body awareness activities, and compassion meditation. MECHANISMS OF ACTION Mindfulness acts to decrease emotional reactivity through cognitive and affective mechanisms of action and neural activation of the cingulate cortex, amygdala, and hippocampus. OUTCOMES Agitation, affect, stress, sleep, discomfort, and communication of need. [Res Gerontol Nurs. 2018; 11(3):137-150.].

Optical imaging of oxidative stress in retinitis pigmentosa (RP) in rodent model

Oxidative stress (OS), which increases during retinal degenerative disorders, contributes to photoreceptor cell loss. The objective of this study was to investigate the changes in the metabolic state of the eye tissue in rodent models of retinitis pigmentosa by using the cryofluorescence imaging technique. The mitochondrial metabolic coenzymes NADH and FADH2 are autofluorescent and can be monitored without exogenous labels using optical techniques. The NADH redox ratio (RR), which is the ratio of the fluorescence intensity of these fluorophores (NADH/FAD), was used as a quantitative diagnostic marker. The NADH RR was examined in an established rodent model of retinitis pigmentosa (RP), the P23H rat, and compared to that of control Sprague-Dawley (SD) rats and P23H NIR treated rats. Our results demonstrated 24% decrease in the mean NADH RR of the eyes from P23H transgenic rats compared to normal rats and 20% increase in the mean NADH RR of the eyes from the P23H NIR treated rats compared to P23H non-treated rats.