Research Roundup: Potential Eye Test for Alzheimer’s and More

Every week there are numerous scientific studies published. Here’s a look at some of the more interesting ones.

Amyloid in the Eyes May Be Indicator of Alzheimer’s

Investigators at the University of California, San Diego (UCSD) found that amyloid plaques in the retinas may be an indicator of amyloid plaques in the brain, which is associated with Alzheimer’s disease. The hope is that it will act as a visible biomarker for detecting disease risk. Amyloid deposits in the eye often occur in patients clinically diagnosed with Alzheimer’s. The researchers at UCSD School of Medicine compared retina tests and brain amyloid in patients from the A4 study and another study, the Longitudinal Evaluation of Amyloid Risk and Neurodegeneration, evaluating the neurodegeneration risk in people with low levels of amyloid. The research was published in Alzheimer’s & Dementia.

“This was a small initial dataset from the screening visit,” said Robert Rissman, senior author of the study and professor of neurosciences at UC San Diego School of Medicine and director of the Biomarker Core for the Alzheimer’s Disease Cooperative Study and Alzheimer’s Disease Research Center at UC San Diego. “It involved eight patients. But these findings are encouraging because they suggest it may be possible to determine the onset, spread and morphology of AD — a preclinical diagnosis — using retinal imaging, rather than more difficult and costly brain scans. We look forward to seeing the results of additional timepoint retinal scans and the impact of solanezumab (a monoclonal antibody) on retinal imaging. Unfortunately, we will need to wait and see and analyze these data when the A4 trial is completed.”

The data to date, however, suggests that non-invasive retinal imaging could be helpful as a biomarker for detecting early-stage AD risk. The next step will be to run a larger study to determine the relationship between retinal amyloid and cerebral amyloid.

Brain Organoids with Complex Neural Activity

Researchers at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA developed brain organoids. These are 3D, brain-like cell complexes grown from human stem cells. And in this case, they demonstrated organized activity similar to that found in living human brains. The organoids allow investigators to study how one person’s cells vary from the norm as well as to run experiments they can’t do in living humans. Once they created several brain organoids derived from the skin cells of healthy people, the scientists studied patterns of electrical activity in them. One approach was by inserting a probe into an organoid to measure brain activity. The other was studying the brain cells function under a microscope. They also developed brain organoids from cells from Rett syndrome patients, a genetic disorder linked to learning delays, repetitive movements and seizures. The organoids seemed normal in structure and organization, but their neural oscillations were abnormal.

Short-Term, Distress Signals from Fat Cells Help Protect the Heart

The “obesity paradox” is when obese people seem to have better short- and medium-term cardiovascular disease markers compared to people who are lean. However, they generally have worse long-term outcomes. Researchers at UT Southwestern Medical Center identified a stress signal that is created by fat but allows cardiac tissues to protect themselves. The metabolic stress of obesity slowly makes fat tissue dysfunctional, resulting in its mitochondria shrinking and dying. Eventually the unhealthy fat is unable to store lipids created by excess calories, and poisons other organs via something called lipotoxicity. Some organs, including the heart, produce a preemptive defense to protect against lipotoxicity, but until now it was unknown how the heart senses fat’s dysfunction. The fat cells, as they grew more dysfunctional, sent out extracellular vesicles filled with small pieces of dying mitochondria. Some of those travel to the heart in the blood and trigger oxidative stress; the heart cells react by producing protective antioxidant molecules.

How High Cholesterol Fuels Cancer

Researchers at Duke University Medical Center identified the mechanisms behind how chronic high cholesterol levels increase the risk of breast cancer and other cancers. Most cancer cells die as they metastasize, which is a stressful cellular process. But the ones that don’t die overcome the stress-induced death mechanism, and it’s fueled by cholesterol. One of the complexities of the topic is that cancers fueled by the hormone estrogen benefitted from derivatives of cholesterol that act like estrogen, which increased cancer growth. But estrogen-negative breast cancers are not dependent on estrogens, but high cholesterol was still linked to worse disease. In their study, they found that migrating cancer cells eat cholesterol in response to stress, and although most die, the ones that survive are better able to withstand ferroptosis, a natural process where cells succumb to stress. These survival-of-the-fittest cells then proliferate and metastasize.

Breast Milk of Mothers Who Received COVID-19 Vaccine Contains Disease-Fighting Antibodies

A study from the University of Florida found that the breast milk of mothers vaccinated against COVID-19 contain significant amounts of antibodies against SARS-CoV-2, the virus that causes COVID-19. Newborns have underdeveloped immune systems. They typically have some disease protection from their mothers, and breast milk offers some passive immunity. The study, which was conducted between December 2020, and March 2021, recruited 21 lactating health care workers who had not contracted COVID-19. They sampled their breast milk and blood three times, before vaccination, after the first dose and after the second dose. They found a robust antibody response in blood and breast milk after the second dose, approximately a hundred-fold increase compared to pre-vaccination levels. The research was published in the journal Breastfeeding Medicine.

“Our findings show that vaccination results in a significant increase in antibodies against SARS-CoV-2 — the virus that causes COVID-19 — in breast milk, suggesting that vaccinated mothers can pass on this immunity to their babies, something we are working to confirm in our ongoing research,” said Joseph Larkin III, senior author of the study an associate professor in the UF/IFAS department of microbiology and cell science.