Creative Minds: Exploring the Role of Immunity in Hypertension

Meena Madhur

Meena Madhur / Credit: John Russell

If Meena Madhur is correct, people with hypertension will one day pay as much attention to their immune cell profiles as their blood pressure readings. A physician-researcher at Vanderbilt University School of Medicine, Nashville, Madhur is one of a growing number of scientists who thinks the immune system contributes to—or perhaps even triggers—hypertension, which increases the risk of stroke, heart disease, kidney disease, and other serious health problems.

About one of every three adult Americans currently have hypertension, yet a surprising number don’t know they have it and less than half have their high blood pressure under control—leading many health experts to refer to the condition as a “silent killer”[1,2]. For many folks, blood pressure control can be achieved through lifestyle changes, such as losing weight, exercising, limiting salt intake, and taking blood pressure medicines prescribed by their health-care provider. Unfortunately, such measures don’t work for everyone, and some people continue to suffer damage to their kidneys and blood vessels from poorly controlled hypertension.

Madhur wants to know whether the immune system might be playing a role, and whether this might hold some clues for developing new, more targeted ways of treating high blood pressure. To get such answers, this practicing cardiologist will use her 2016 NIH Director’s New Innovator Award to conduct sophisticated, single-cell analyses of the immune systems of people with and without hypertension. Her goal is to produce the most comprehensive catalog to date of which human immune cells might be involved in hypertension.

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Regenerative Medicine: Making Blood Stem Cells in the Lab

Endothelial cells becoming hematopoietic stem cells

Caption: Arrow in first panel points to an endothelial cell induced to become hematopoietic stem cell (HSC). Second and third panels show the expansion of HSCs over time.
Credit: Raphael Lis, Weill Cornell Medicine, New York, NY

Bone marrow transplants offer a way to cure leukemia, sickle cell disease, and a variety of other life-threatening blood disorders.There are two major problems, however: One is many patients don’t have a well-matched donor to provide the marrow needed to reconstitute their blood with healthy cells. Another is even with a well-matched donor, rejection or graft versus host disease can occur, and lifelong immunosuppression may be needed.

A much more powerful option would be to develop a means for every patient to serve as their own bone marrow donor. To address this challenge, researchers have been trying to develop reliable, lab-based methods for making the vital, blood-producing component of bone marrow: hematopoietic stem cells (HSCs).

Two new studies by NIH-funded research teams bring us closer to achieving this feat. In the first study, researchers developed a biochemical “recipe” to produce HSC-like cells from human induced pluripotent stem cells (iPSCs), which were derived from mature skin cells. In the second, researchers employed another approach to convert mature mouse endothelial cells, which line the inside of blood vessels, directly into self-renewing HSCs. When these HSCs were transplanted into mice, they fully reconstituted the animals’ blood systems with healthy red and white blood cells.

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AIDS Vaccine Research: Better By Design?

OD-GT8 60mer

Caption: eOD-GT8 60mer nanoparticle based on the engineered protein eOD-GT8. Yellow shows where eOD-GT8 binds antibodies; white is the protein surface outside the binding site; light blue indicates the sugars attached to the protein; dark blue is the nanoparticle core to which eOD-GT8 has been fused.
Credit: Sergey Menis and William Schief, The Scripps Research Institute

A while ago, I highlighted a promising new approach for designing a vaccine against the human immunodeficiency virus (HIV), the cause of AIDS. This strategy would “take the immune system to school” and teach it a series of lessons using several vaccine injections—each consisting of a different HIV proteins designed to push the immune system, step by step, toward the production of protective antibodies capable of fending off virtually all HIV strains. But a big unanswered question was whether most people actually possess the specific type of precursor immune cells that that can be taught to produce antibodies that kill HIV.

Now, we may have the answer [1]. In a study published in the journal Science, a research team, partly supported by NIH, found that the majority of people do indeed have these precursor cells. While the total number of these cells in each person may be low, this may be all that’s needed for the immune system to recognize a vaccine. Based in part on these findings, researchers plan to launch a Phase 1 clinical trial in human volunteers to see if their latest engineered protein can find these precursor cells and begin coaxing them through the complicated process of producing protective antibodies.

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Molecular Answers Found for a Mysterious Rare Immune Disorder

Harry Hill and Patient Images

Caption: Helping to solve a medical mystery. Top left, University of Utah’s Harry Hill; Bottom, CVID patient Roma Jean Ockler; Right, Ockler showing the medication that helps to control her CVID.
Credit: Jeffrey Allred, Deseret News

When most of us come down with a bacterial infection, we generally bounce back with appropriate treatment in a matter of days. But that’s often not the case for people who suffer from common variable immunodeficiency (CVID), a group of rare disorders that increase the risk of life-threatening bacterial infections of the lungs, sinuses, and intestines. CVID symptoms typically arise in adulthood and often take many years to diagnose and treat, in part because its exact molecular causes are unknown in most individuals.

Now, by combining the latest in genomic technology with some good, old-fashioned medical detective work, NIH-funded researchers have pinpointed the genetic mutation responsible for an inherited subtype of CVID characterized by the loss of immune cells essential to the normal production of antibodies [1]. This discovery, reported recently in The New England Journal of Medicine, makes it possible at long last to provide a definitive diagnosis for people with this CVID subtype, paving the way for them to receive more precise medical treatment and care. More broadly, the new study demonstrates the power of precision medicine approaches to help the estimated 25 to 30 million Americans who live with rare diseases [2].

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Vaccine Research: New Tactics for Tackling HIV

HIV-infected Immune Cell

Caption: Scanning electron micrograph of an HIV-infected immune cell.
Credit: National Institute of Allergy and Infectious Diseases, NIH

For many of the viruses that make people sick—think measles, smallpox, or polio—vaccines that deliver weakened or killed virus encourage the immune system to produce antibodies that afford near complete protection in the event of an exposure. But that simple and straightforward approach doesn’t work in the case of human immunodeficiency virus (HIV), the virus that causes AIDS. In part, that’s because our immune system is poorly equipped to recognize HIV and mount an attack against the infection. To make matters worse, HIV has a habit of quickly mutating as it multiplies.That means, in order for an HIV vaccine to be effective, it must induce antibodies capable of fighting against a wide range of HIV strains. For all these reasons, the three decades of effort to develop an HIV vaccine have turned out to be enormously challenging and frustrating.

But now I’m pleased to report that NIH-funded scientists have taken some encouraging strides down this path. In two papers published in Science [1, 2] and one in Cell [3], researchers presented results of animal studies that support what most vaccine experts have come to suspect: the immune system is in fact capable of producing the kind of antibodies that should be protective against HIV, but it takes more than one step to get there. In effect, a successful vaccine strategy has to “take the immune system to school,” and it requires more than one lesson to pass the final exam. Specifically, what’s needed seems to be a series of shots—each consisting of a different engineered protein designed to push the immune system, step by step, toward the production of protective antibodies that will work against virtually all HIV strains.

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