Research Roundup: Lasting Immunity to COVID-19 and More
Every week there are numerous scientific studies published. Here’s a look at some of the more interesting ones.
Multiple Studies Suggest Lasting Immunity to COVID-19 After Infection
Although probably not enough time has passed to know definitively, several studies are now suggesting that even mild cases of COVID-19 stimulate lasting immune responses, not only in disease-fighting antibodies, but in B- and T-cells.
It’s difficult, probably impossible, to predict how long those immune responses will last, but many of the researchers believe the results are promising for long-term protection.
“This is exactly what you would hope for,” Marion Pepper, an immunologist at the University of Washington and an author of a study currently being reviewed by the journal Nature. “All the pieces are there to have a totally protective immune response.”
Pepper notes that the protective effects can’t be completely evaluated until there is proof that people exposed to the virus a second time can fight it off. But the data suggests the immune system is indeed able to fight resistance a second time. Some of this qualification comes from unconfirmed reports of people being reinfected by the virus.
Antibody responses are typically relatively short-lived, disappearing from the blood weeks or months after being produced. Generally, the majority of the B-cells that produce antibodies die off, too. But the body keeps some longer-lived B-cells that are able to manufacture virus-fighting antibodies should the immune system be triggered by re-exposure to the virus. Some stay in the bloodstream while others wait in the bone marrow where they manufacture small numbers of antibodies that can sometimes be observed years, even decades later. Several studies, some by Bhattacharya and Pepper, have identified antibodies at low levels in the blood months after people recovered from COVID-19.
“The antibodies decline, but they settle in what looks like a stable nadir,” Bhattacharya said. These have been observed about three months after symptoms show up. “The response looks perfectly durable.”
Additional studies, including one published in the journal Cell, have isolated T-cells from recovered patients that can attack SARS-CoV-2. In laboratory studies, the T-cells produced signals to fight the virus and cloned themselves in large numbers to fight the potential infection.
“This is very promising,” said Smita Iyer, an immunologist at the University of California, Davis, who was not involved in the new studies, but has researched immune responses to the novel coronavirus in rhesus macaques. “This calls for some optimism about herd immunity, and potentially a vaccine.”
It's still has not been definitely determined if milder cases of COVID-19 will lead to long-term or even medium-term immunity. There have been some studies that suggest it does not and some newer studies suggesting it does. Iyer notes that the recent paper indicates, “You can still get durable immunity without suffering the consequences of infection.”
This idea is reinforced by Eun-Hyung Lee, an immunologist at Emory University who was not involved in these studies. He told The New York Times, “Yes, you do develop immunity to this virus, and good immunity to this virus. That’s the message we want to get out there.”
Why Seasonal Flu Vaccines Only Last a Year
As most everyone knows, flu vaccines only last about a year. Some of this is related to viral mutations. But in fact, the actual immunity itself caused by the vaccine does not appear to last longer than a year, even though the flu vaccine increases the number of antibody-producing cells specific for the flu in the bone marrow. Researchers out of Emory Vaccine Center found that for most newly-generated plasma cell lineages, between 70 and 99% of the cells were gone after one year, but that the levels of antibody-secreting cells in blood correlated with long-term response in the bone marrow.
Gut Bacteria Can Help Immuno-Oncology Therapies
Researchers with the University of Calgary identified gut bacteria that help our immune system fight cancerous tumors. This also helped provide more information about why immunotherapy works in some cases, but not others. By combining immunotherapy with specific microbial therapy, they believe they can help the immune system and immunotherapy be more effective in treating three types of cancer: melanoma, bladder and colorectal cancers. They found that specific bacteria were essential for immunotherapy to work in colorectal cancer tumors in germ-free mice. The bacteria produced a small molecule called inosine that interacts directly with T-cells and together with immunotherapy.
An Online Calculator to Predict Stroke Risk
Scientists at the University of Virginia Health System developed an online tool that measures the severity of a patient’s metabolic syndrome, a mix of conditions that includes high blood pressure, abnormal cholesterol levels and excess body fat. With it, they can then predict the patient’s risk for ischemic stroke. The study discovered that stroke risk increased consistently with metabolic syndrome severity even in patients that did not have diabetes. The tool is available for free at https://metscalc.org/.
A Link Between Autism and Cholesterol
Researchers at Harvard Medical School, Massachusetts Institute of Technology (MIT) and Northwestern University identified a subtype of autism that is the result of a cluster of genes that regulate cholesterol metabolism and brain development. They believe this information can help design precision-targeted therapies for this specific type of autism and improve screening efforts for earlier diagnosis of autism. They analyzed the DNA from brain samples that they then confirmed with the medical records of autistic individuals. They found that children with autism and their parents had significant alterations in lipid blood. However, there is much more to be understood, emphasizing the complexity of autism, which is affected by a variety of genetic and environmental factors.
Researchers Grow First Functioning Mini Human Heart Model
Investigators with Michigan State University grew the first miniature human heart model in the laboratory that is complete with all primary heart cell types and a functioning structure of chambers and vascular tissue. They utilized induced pluripotent stem cells which were obtained from consenting adults and created a functional mini heart in a few weeks. The primary value was in giving them an unprecedented view into how a fetal heart develops.
“In the lab, we are currently using heart organoids to model congenital heart disease—the most common birth defect in humans affecting nearly 1% of the newborn population,” said Aitor Aguirre, senior author and assistant professor of biomedical engineering at MSU’s Institute for Quantitative Health Science and Engineering. “With our heart organoids, we can study the origin of congenital heart disease and find ways to stop it.”
Another area of focus is that improving on the final organoid will help with future research. Current heart organoids are not identical yet to human hearts and so are flawed in their use as research models.