Aged complement factor H knockout mice kept in a clean barriered environment have reduced retinal pathology

Age-related macular degeneration (AMD) is the largest cause of visual loss in those over 60 years in the West and is a condition increasing in prevalence. Many diseases result from genetic/environmental interactions and 50% of AMD cases have an association with polymorphisms of the complement system including complement factor H. Here we explore interactions between genetic predisposition and environmental conditions in triggering retinal pathology in two groups of aged complement factor H knock out (Cfh−/−) mice. Mice were maintained over 9 months in either a conventional open environment or a barriered pathogen free environment. Open environment Cfh−/− mice had significant increases in subretinal macrophage numbers, inflammatory and stress responses and reduced photoreceptor numbers over mice kept in a pathogen free environment. Hence, environmental factors can drive retinal disease in these mice when linked to complement deficits impairing immune function. Both groups of mice had similar levels of retinal amyloid beta accumulation. Consequently there is no direct link between this and inflammation in Cfh−/− mice

Mitochondrial decline precedes phenotype development in the complement factor H mouse model of retinal degeneration but can be corrected by near infrared light

AbstractMitochondria produce adenosine triphosphate (ATP), critical for cellular metabolism. ATP declines with age, which is associated with inflammation. Here, we measure retinal and brain ATP in normal C57BL/6 and complement factor H knockout mice (Cfh−/−), which are proposed as a model of age-related macular degeneration. We show a significant premature 30% decline in retinal ATP in Cfh−/− mice and a subsequent shift in expression of a heat shock protein that is predominantly mitochondrial (Hsp60). Changes in Hsp60 are associated with stress and neuroprotection. We find no differences in brain ATP between C57BL/6 and Cfh−/− mice. Near infrared (NIR) increases ATP and reduces inflammation. ATP decline in Cfh−/− mice was corrected with NIR which also shifted Hsp60 labeling patterns. ATP decline in Cfh−/− mice occurs before inflammation becomes established and photoreceptor loss occurs and may relate to disease etiology. However, ATP levels were corrected with NIR. In summary, we provide evidence for a mitochondrial basis for this disease in mice and correct this with simple light exposure known to improve mitochondrial function

Viewing Ageing Eyes: Diverse Sites of Amyloid Beta Accumulation in the Ageing Mouse Retina and the Up-Regulation of Macrophages

Amyloid beta (Aβ) accumulates in the ageing central nervous system and is associated with a number of age-related diseases, including age-related macular degeneration (AMD) in the eye. AMD is characterised by accumulation of extracellular deposits called drusen in which Aβ is a key constituent. Aβ activates the complement cascade and its deposition is associated with activated macrophages. So far, little is known about the quantitative measurements of Aβ accumulation and definitions of its relative sites of ocular deposition in the normal ageing mouse. METHODOLOGY/PRINCIPAL FINDINGS: We have traced Aβ accumulation quantitatively in the ageing mouse retina using immunohistochemistry and Western blot analysis. We reveal that it is not only deposited at Bruch's membrane and along blood vessels, but unexpectedly, it also coats photoreceptor outer segments. While Aβ is present at all sites of deposition from 3 months of age, it increases markedly from 6 months onward. Progressive accumulation of deposits on outer segments was confirmed with scanning electron microscopy, revealing age-related changes in their morphology. Such progress of accumulation of Aβ on photoreceptor outer segments with age was also confirmed in human retinae using immunohistochemistry. We also chart the macrophage response to increases in Aβ showing up-regulation in their numbers using both confocal laser imaging of the eye in vivo followed by in vitro immunostaining. With age macrophages become bloated with cellular debris including Aβ, however, their increasing numbers fail to stop Aβ accumulation. CONCLUSIONS: Increasing Aβ deposition in blood vessels and Bruch's membrane will impact upon retinal perfusion and clearance of cellular waste products from the outer retina, a region of very high metabolic activity. This accumulation of Aβ may contribute to the 30% reduction of photoreceptors found throughout life and the shortening of those that remain. The coating of Aβ on outer segments may also have an impact upon visual function with ag

A day in the life of mitochondria reveals shifting workloads

Mitochondria provide energy for cellular function. We examine daily changing patterns of mitochondrial function and metabolism in Drosophila in vivo in terms of their complex (I-IV) activity, ATP production, glycolysis, and whole fly respiration in the morning, afternoon and night. Complex activity and respiration showed significant and unexpected variation, peaking in the afternoon. However, ATP levels by contrast are >40% greater in the morning and lowest at night when glycolysis peaks. Complex activity modulation was at the protein level with no evidence for differential transcription over the day. Timing differences between increased ATP production and peaks of complex activity may result from more efficient ATP production early in the day leaving complex activity with spare capacity. Optical stimulation of mitochondria is only possible in the mornings when there is such spare capacity. These results provide first evidence of shifts in cellular energy capacity at the organism level. Understanding their translation may be significant to the chosen timing of energy demanding interventions to improve function and health

The effect of photobiomodulation on the brain during wakefulness and sleep

Over the last seventy years or so, many previous studies have shown that photobiomodulation, the use of red to near infrared light on body tissues, can improve central and peripheral neuronal function and survival in both health and in disease. These improvements are thought to arise principally from an impact of photobiomodulation on mitochondrial and non-mitochondrial mechanisms in a range of different cell types, including neurones. This impact has downstream effects on many stimulatory and protective genes. An often-neglected feature of nearly all of these improvements is that they have been induced during the state of wakefulness. Recent studies have shown that when applied during the state of sleep, photobiomodulation can also be of benefit, but in a different way, by improving the flow of cerebrospinal fluid and the clearance of toxic waste-products from the brain. In this review, we consider the potential differential effects of photobiomodulation dependent on the state of arousal. We speculate that the effects of photobiomodulation is on different cells and systems depending on whether it is applied during wakefulness or sleep, that it may follow a circadian rhythm. We speculate further that the arousal-dependent photobiomodulation effects are mediated principally through a biophoton – ultra-weak light emission – network of communication and repair across the brain

Scanning electron micrographs of photoreceptor outer segments taken from animals at 3, 6, 12 and 24 months of age.

<p>In each case the right hand panel is a higher magnification of that on the left and the orientation is such that the RPE would be to the top and the outer nuclear layer to the bottom. Even at 3 months of age deposits can be found on outer segments, however they are more common towards the tip of the outer segment than the base. They are largely spherical in morphology or have rounded edges. By 6 months, their coating has increased and the deposits are present along the length of the outer segment. At 12 months the deposits have thickened, but also appear to have changed qualitatively (See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013127#pone-0013127-g007" target="_blank">Figure 7</a>). At 24 months while thick deposits remain the tips of many outer segments have enlarged and those that remain are shorter making direct comparison with earlier stages difficult.</p

Aβ staining in human outer retina from individuals aged 31, 47, 80 and 90 years.

<p>This was undertaken on retinae separated from the RPE. Aβ is red and the outer nuclear layer (ONL) is blue. The outer segments (OS) are positive for Aβ but the intensity of the staining increases with age. In spite of this, the overall progression of Aβ accumulation here mirrors that found in mice.</p

Retinal blood vessels stained for Aβ.

<p>A. Inner retinal vessels stained for Aβ (red), Iba-1 (green) and neuronal cell bodies (blue) at 24 months. The amyloid deposits can be seen to be at focal points along the vessel rather than being continuous. B. Choroidal vessels also accumulated Aβ, however, the accumulation of this material appeared to be specific to a sub-group of vessels with other showing no sign of Aβ accumulation. This is taken from a 12 months old animal. C. Immunostaining of retinal section of a 12 months old animal using the colorimetric method (3,3-diaminobenzidine) to confirm the presence of Aβ in the outer segment of the photoreceptor and in the blood vessels. D. Negative control of the colorimetric staining showing the absence of staining.</p

Retinal imaging and macrophage histology.

<p>A. Scanning laser ophthalmoscope images of the retinae of mice taken at 3, 6, 12 and 24 months of age. With time there is an accumulation of fluorescent point sources. B. The images are overlaid with the eyecups of a 12 months old mouse once they have been stained for Iba-1 to reveal macrophages and Aβ. This shows that many of the point sources are macrophages containing Aβ (indicated with arrows). These are arranged in a grid like pattern. C. A higher power image of Aβ containing macrophages of a 12 months old mouse. D. The number of macrophages present in the whole mounts at progressive ages. There are significant increases at 12 and 24 months (see text for statistics).</p