Breaking News
April 21, 2018 - Americans world’s biggest TV addicts, watching four hours a day
April 21, 2018 - Investigational drug may help increase protein levels in babies with spinal muscular atrophy
April 21, 2018 - Study shows distinctions between age groups in predicting and responding to stress at home
April 21, 2018 - Aziyo Biologics, BIOTRONIK enter into US co-distribution agreement
April 21, 2018 - Opiate Use Linked to Early Mortality in IBD Patients
April 21, 2018 - Online ads help pregnant smokers quit
April 21, 2018 - Opioid pain medications may not be safe for hemodialysis patients
April 21, 2018 - Rare variants in non-coding DNA inherited from parents heighten autism risk
April 21, 2018 - A needleless glucose monitor for diabetes patients
April 21, 2018 - BD introduces new informatics and automation solutions for clinical laboratories
April 21, 2018 - Turn Chores Into a Fitness Routine
April 21, 2018 - DNA methylation plays key role in stem cell differentiation
April 21, 2018 - Scientists find link between soil metals and cancer mortality
April 21, 2018 - Experts discuss implications of low calcium intake in global population
April 21, 2018 - GNA Biosolutions to display Pharos V8 Laser PCR instrument at Analytica trade fair
April 21, 2018 - People with vitamin D deficiency may be at greater risk of diabetes
April 21, 2018 - Study findings could open new possibilities for treating cancer with adenovirus
April 21, 2018 - People who use medical marijuana have higher rates of prescription drug use, study finds
April 21, 2018 - Study debunks ‘myth’ that strenuous exercise dampens immunity
April 21, 2018 - FDA approves marijuana based medication for epilepsy treatment
April 21, 2018 - Researchers find novel genes for longevity in mammals
April 21, 2018 - GNA Biosolutions and project partners launch new research project to develop TB diagnostic platform for POC applications
April 21, 2018 - Scientists identify gene responsible for evolution of recombination rates
April 21, 2018 - UConn researchers develop new composite for healing broken load-bearing bones
April 21, 2018 - Study challenges use of whole-brain radiation for small-cell lung cancer patients with brain metastases
April 21, 2018 - People who become physically active after heart attack more likely to live longer, shows research
April 21, 2018 - CPRIT awards $2 million grant to push forward breast cancer research in West Texas
April 21, 2018 - Unhealthy diet damages the development of immature fat cells, study shows
April 21, 2018 - Consumption of protein supplements with meals may provide better weight control
April 21, 2018 - 4 Types of Foods to Help Boost Your Memory
April 21, 2018 - How did gonorrhea become a drug-resistant superbug?
April 21, 2018 - DePuy Synthes announces clinical results related to use of CORAIL Hip System Femoral Stems
April 21, 2018 - New initiative launched to support goals of Human Cell Atlas
April 20, 2018 - Teen patient gets a new lease on life
April 20, 2018 - Cancer Australia launches new framework to improve outcomes for lung cancer patients
April 20, 2018 - ‘Gut-on-a-chip’ model recreates intestinal matrix critical for nutrient absorption
April 20, 2018 - Researchers develop new drug-testing platform for epilepsy
April 20, 2018 - FDA Alert: NxtGen Botanicals Maeng Da Kratom by NGB Corp.: Recall
April 20, 2018 - Pelizaeus-Merzbacher-like disease type 1 – Genetics Home Reference
April 20, 2018 - Tick-borne diseases reach epidemic levels, panel says
April 20, 2018 - A potential “male pill” without side effects
April 20, 2018 - Researchers discover new information related to rare form of leukemia
April 20, 2018 - Researchers find crucial links between dopamine and avoidance behavior
April 20, 2018 - UGA scientist creates system for efficient detection of foodborne pathogens
April 20, 2018 - Social Support of Autonomy Tied to Better Glycemic Control in DM
April 20, 2018 - Study reports use of nutritional ketosis with mobile app intervention could reverse Type 2 diabetes
April 20, 2018 - New microscopy techniques allow quasi-biochemical studies on living T cells
April 20, 2018 - Study shows connection between muscular strength and brain health
April 20, 2018 - Ecolab introduces Life Sciences cleanroom program in North America
April 20, 2018 - Normal weight people with fat belly may have more chance of heart problems
April 20, 2018 - Male fruit flies like sex and alcohol
April 20, 2018 - Meditation could help reduce anxiety levels and some heart health risk factors
April 20, 2018 - Improving job prospects unlikely to control opioid epidemic
April 20, 2018 - Skin Sensor Might Someday Track Alcoholics’ Booze Intake
April 20, 2018 - The relevance of GABA for diabetes highlighted in two new studies
April 20, 2018 - Novel method enables fast and noninvasive assessment of tumor status
April 20, 2018 - IU psychologist receives NIH grant to study earliest phases of language learning in children
April 20, 2018 - Walking fast lowers risk of hospitalization in heart patients, shows study
April 20, 2018 - Study reveals surprising insights into RNA-binding proteins
April 20, 2018 - Young victims of cyberbullying twice as likely to attempt suicide and enact suicidal behavior
April 20, 2018 - Role of UBE3A enzyme in Angelman syndrome
April 20, 2018 - NovaDigm Therapeutics initiates NDV-3A Phase 2a study for reduction of S. aureus in military trainees
April 20, 2018 - High-tech microscope reveals how cancer-causing virus anchors itself to human DNA
April 20, 2018 - Experimental compound reduces destructive inflammation to improve stroke outcome
April 20, 2018 - The May issue of Drug Discovery Today is a Special Issue and will be published very soon
April 20, 2018 - Larger families linked to heightened tooth loss risk for moms
April 20, 2018 - Scientists develop tiny fluorescent probe that seeks out GLUT5 and detects cancer cells
April 20, 2018 - The Swedish Childhood Cancer Foundation awards grant to KI researchers
April 20, 2018 - AMSBIO’s MC-Easy minicircle technology allows sustained transgene expression in quiescent cells and tissues
April 20, 2018 - Researchers use optogenetics to treat chronic pain
April 20, 2018 - Discovery of 100 new genes may aid research into pigmentation
April 20, 2018 - AYOXXA introduces new LUNARIS Mouse 12-Plex Th17 Kit for quantitative analysis of Th17 cell biology
April 20, 2018 - Compound derived from immune cells treats psoriasis in mice
April 20, 2018 - GABA-transaminase deficiency – Genetics Home Reference
April 20, 2018 - Key heart risks decline for older Americans
April 20, 2018 - UD professor wins $2.3 million grant from NIH for research on Achilles tendinopathy
April 20, 2018 - Researchers discover unique protein in malaria parasite that could be new drug target
April 20, 2018 - Bio-Techne expands automation capabilities of popular RNAscope ISH technology
April 20, 2018 - Smartphone app effective in promoting proper child car seat practices
April 20, 2018 - Nutraceuticals could play an important role in preventing heart disease
Immune cells can repopulate in the retina after elimination, mice study shows

Immune cells can repopulate in the retina after elimination, mice study shows

image_pdfDownload PDFimage_print

Immune cells called microglia can completely repopulate themselves in the retina after being nearly eliminated, according to a new study in mice from scientists at the National Eye Institute (NEI). The cells also re-establish their normal organization and function. The findings point to potential therapies for controlling inflammation and slowing progression of rare retinal diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD), the most common cause of blindness among Americans 50 and older. A report on the study was published online today in Science Advances. The NEI is part of the National Institutes of Health.

“Neuroinflammation is an important driver of the death of neurons in retinal diseases,” said Wai T. Wong, M.D., Ph.D., chief of the NEI Section on Neuron-Glia Interactions in Retinal Disease, and the study’s lead investigator. “Our study is foundational for understanding ways to control the immune system in the retina.” Control of the immune system is important for developing new treatments for a variety of eye conditions, including AMD, RP, or for certain types of retinal injury.

The retina is a thin layer of cells in the back of the eye that includes light-sensing photoreceptor cells and other neurons involved in transmitting visual information to the brain. Mixed in with these cells are microglia, specialized immune cells that help maintain the health of the retina and the function of retinal neurons. Microglia are also present in other parts of the central nervous system, including the brain. In a healthy retina, communication between neurons and microglia is important for maintaining the neuron’s ability to send signals to the brain. When the retina is injured, however, microglia have an additional role: They migrate quickly to the injury site to remove unhealthy or dying cells. However, they can also remove healthy cells, contributing to vision loss. Studies show that in degenerative retinal disorders like AMD and RP, inhibiting or removing microglia can help retain photoreceptors, and thus slow vision loss. But return of microglia is still important to support the retina’s neurons.

Wong and colleagues were interested in understanding what happens in the retina after microglia have been eliminated, particularly whether the cells could return to their normal arrangement and fulfill their normal functions. To test this, they depleted the microglia in the retinas of mice using the drug PLX5622 (Plexxikon), which blocks the microglial CSF-1 receptor. Microglia depend on continuous signals through this receptor for survival. Interruption of this signaling for several days caused the microglia to nearly disappear, leaving just a few cells clustered around the optic nerve-;the cable-like bundle of nerve fibers that carries signals from the retina to the brain-;in the mouse retinas. Since loss of microglia for a short time doesn’t affect the function of neurons, removing microglia temporarily-;in order to reduce inflammation for example-;could potentially be useful as a therapeutic intervention for degenerative or inflammatory disorders of the retina.

“If we were to get rid of the microglia while a large, inappropriate immune response was happening,” said Wong, “we might be able to miss the worst of the inflammation, but still come back into balance at a later point in time. We could hit pause on the immune system in the retina in a directed way.”

Within 30 days after stopping the drug, Wong and colleagues found that the microglia had repopulated the retina, returning to normal density after 150 days. Using a novel method for visually tracking microglial movements in the retina, they determined that the returning microglia initially grew in clusters near where the optic nerve leaves the eye. Gradually, new microglia expanded outwards towards the edges of the retina. Over time, the cells re-established an even distribution across and through the various layers of the retina.

“The organization of these immune cells is quite elaborate, and all the organization comes right back,” Wong said. “We can actually image the eye and watch these cells divide and split and migrate as part of the repopulation response.”

To test whether the new microglia were fully functional, the researchers used an injury model where photoreceptor cells are damaged by bright light. The new microglia were able to activate and migrate to the injury site normally. In addition, using electroretinography (ERG), a technique that measures the electrical signals generated by retinal neurons after being stimulated with light, the researchers tested the health of different groups of neurons. They found that the microglia were able to communicate with and fully maintain the function of neurons in the retina, especially when the depletion was short-lived.

Drugs that remove microglia are now administered systemically, affecting the brain and other parts of the central nervous system. More research is needed to find ways to administer these drugs directly to the retina, sparing off-target tissues.

Source:

https://nei.nih.gov/content/immune-cells-retina-can-spontaneously-regenerate

Tagged with:

About author

Related Articles