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his song, through its simple refrain, offered perhaps the single best anthem of the 1960s, a time when, indeed, many changes were afoot. Part protest and part prophesy, "Times" observed the extraordinary events of the early 1960s and anticipated the far-reaching changes that were to come in music, politics, entertainment and science -- changes that would reach a crescendo by the end of the decade, define a generation, and reverberate even today.

In the 1960s, a senior woman research scientist was relatively rare. Today it is not, according to the latest definitive study on the subject, a 2001 report by the National Research Council, From Scarcity to Visibility: Gender Differences in the Careers of Doctoral Scientists and Engineers.

The National Research Council reports that the number of women receiving Ph.D.'s in science and engineering increased 350 percent between 1973 and 1995. Over the same period, the percentage of women employed as full-time academic researchers nearly tripled, from 8 to 23 percent. And in 1995, the report adds, more than 40 percent of new life science Ph.D.'s were awarded to women.

And yet, in 1995, when three investigators at The Scripps Research Institute were awarded a multi-year "program project" grant sponsored by the National Institutes of Health, they were the only all-woman program project grant at that time.

"To have the strength in one department of a sufficient number of senior women is unique," says Linda Sherman, Ph.D., who like her coinvestigators was a young girl when Bob Dylan was singing of changing times.

A PROGRAM WITH THREE PROJECTS

The grant, which was renewed through 2005, funds a program focusing on the basic mechanisms of autoimmunity -- diseases involving immune responses to self tissues. It combines the research interests and expertise of the laboratories of Sherman, Nora Sarvetnick, Ph.D., and Sue Webb, Ph.D., in The Scripps Research Institute's Department of Immunology.

The three have independent laboratories and separate grants as well. The program project grant funds studies in all three labs that focus on the specific goal of better understanding how the immune system goes awry in the development of Type 1 diabetes. It allows them to pool their resources and draw on their individual strengths to facilitate progress toward this goal. They publish together, foster collaboration among their post docs, and use several "core" facilities with shared resources.

"We collaborate and use each of our expertise to get a bigger picture," says Sherman. That bigger picture addresses the cellular and molecular causes of autoimmune diseases like Type 1 diabetes, focusing on the role of T lymphocytes.

"[The National Institutes of Health grant] developed out of a mutual interest I had with Linda and Nora on how T-cells are regulated," says Webb. "It seemed logical that we should get together and see how the regulatory mechanisms we were looking at are compromised in the development of diabetes."

"In autoimmunity, the balance [between cells and their regulation] has been disturbed," Webb adds. "If we knew [how to maintain the balance], then we would probably be able to make predictions about how to get it back when it goes off."

"HORROR AUTOTOXICUS"

Type 1 diabetes is one of around 80 known autoimmune diseases -- a collection that includes such diverse and chronic ailments as multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, and lupus. Nobel laureate and immunology pioneer Paul Ehrlich coined the term "autoimmune" in 1900, when he recognized the need for the body to avoid making an immune reaction to its own cells. He called this "horror autotoxicus" (fear of self-poisoning).

In these autoimmune diseases, which affect women about three times as often as men, the body's immune system attacks the body's own tissues. In the case of Type 1 (insulin dependent) diabetes, for instance, the insulin-producing beta cells in the so-called islets of Langerhans situated in the pancreas are destroyed by T cells. These cells are the body's only source of insulin -- a protein responsible for regulating blood glucose levels. As the beta cells are destroyed, insulin production becomes limited.

Without insulin, the glucose in the bloodstream increases and is maintained at levels much higher than normal. Over time, this can lead to nerve and kidney damage, impaired eyesight, and an increased risk of developing heart disease, high blood pressure, stroke and vascular degeneration.

The therapy of choice for the disease is to inject insulin, and before the discovery and isolation of insulin in the 1920s, having Type 1 diabetes meant certain death. Though insulin replacement is a rational treatment, Type 1 diabetes is still a chronic disease for which there is no prevention and no cure. About 30,000 Americans develop Type 1 diabetes every year.

Many of these new cases are in children. Type 1 diabetes is one of the most prevalent chronic diseases among children in the United States. Statistics compiled by the National Diabetes Data Group of the National Institute of Diabetes and Digestive and Kidney Diseases and published in the 1995 National Institutes of Health publication Diabetes in America, showed that over 120,000 children and adolescents -- approximately one in every 400 to 500 -- have Type 1 diabetes, and every year about 13,000 more children and adolescents develop it.

"Our goal is to understand the causes of Type 1 diabetes [so that] we might be able to go on and design therapies," says Sarvetnick.

AUTOREACTIVE T CELLS

The factors that initiate the activation of T cells that go on to destroy the insulin-producing cells in the pancreas are not yet understood. One hypothesis with significant support is that Type 1 diabetes occurs after a person contracts a common virus that infects cells in the pancreas. During the viral infection, the body makes an adaptive immune response, and in most people, this response is specific for the virus -- the T cells of those people selectively target and eliminate cells that are infected with the virus, and they recover normally.

In Type 1 diabetes, the killing proceeds out of control. The T cells become autoreactive, vigorously attacking not only the infected islet cells but the healthy ones as well. The T cells eventually destroy all the insulin-producing cells in the body, causing a depletion of insulin in the bloodstream.

However, the precise, detailed mechanisms and molecular interactions that lead to Type 1 diabetes are not clear. Nor is it clear why many more people are infected with the implicated viruses than develop the disease.

"We're trying to understand how people who are resistant to this disease counter-regulate these processes," says Sarvetnick, "and which molecules [and pathways] they work through."

"The key thing is to discover the pathways and see how we can restore immune tolerance in these potentially devastating pathways," she adds.

HOW T CELLS ARE REGULATED

Immune responses are normally regulated by a variety of mechanistic "pathways." These pathways are crucial because it is a breakdown in their proper control that permits T cells to kill healthy insulin-producing cells. Without the breakdown of control, the disease would never develop.

There are two major types of T cells in the body, and Webb's portion of the program project grant concentrates on how one of these two types, the "helper" T cells, is regulated.

Helper T cells are often referred to as "CD4+ cells" because of the distinct expression of CD4 molecules on the cell surface. The primary function of these cells is to provide help to various components of the immune system to insure adequate responses to viruses, bacteria, and other microbial pathogens. Helper T cells promote the activity of killer T cells, natural killer cells, and macrophages that destroy the pathogen along with any pathogen-infected host cells.

Helper T cells also activate B (bone marrow-derived) cells to produce antibodies, proteins that specifically bind to the pathogen, inhibiting its growth and ability to colonize the body. CD4+ cells activate these various cell types primarily by secreting small chemical messengers, called cytokines, that bind to specific receptors on the target cells.

Before secreting cytokines, however, CD4+ cells must be activated themselves. This requires specific recognition of pieces of the pathogen that have been ingested and displayed on the surface of cells referred to as "antigen presenting cells." This complicated process involves multiple cell types and a number of interacting cell surface receptors and costimulatory molecules.

This initial recognition of antigen, termed T cell "priming," must occur under appropriate conditions in order to develop helper activity. Webb is particularly interested in the events that occur during priming of CD4 cells and is trying to determine the constellation of cell surface molecules important in developing T cells that cause diabetes or alternatively regulate or prevent disease.

A PROD PRIOR TO DESTRUCTION

The other major type of T cell in the body, which is also an important player in diabetes, is variously referred to as the "cytotoxic T lymphocyte," the "killer T cell," or because of the molecule it displays on its outer surface, the "CD8 T cell."

They are the mass murderers of the immune system.

Killer T cells, like all T cells, undergo a complicated maturation process in the thymus when they are raised from precursors. During this maturation, 95 percent of the immature T cells are killed before they are ever released into the bloodstream, based on how they recognize antigen -- specifically the "self" antigen that normal cells display. All T cells need to be able to recognize self tissue weakly, which seems to be important for maintaining the proper levels of T cells in the body. T cells that do not have the ability to recognize self antigen at all are selected out, as are the T cells that are too auto-reactive (these would kill perfectly healthy cells displaying the antigen). Ultimately, the thymus produces T cells that have the potential to react strongly with foreign antigen but only weakly with self, including islet cells of the pancreas.

But in diabetes something changes, and the killer T cells may be activated to attack and kill the insulin-producing islet cells for which they have only low affinity (weak recognition).

Normally killer T cells with weak affinity for pancreatic islet cells would ignore the uninfected islet cells and kill only the infected ones. But during diabetes, the immune system targets antigen that is displayed on all islet cells, and killer T cells that normally would have only weak affinity for this "self" antigen are enhanced. These killer T cells are "prodded" by helper T cells to kill the islet cells and keep killing them until they are all gone.

Sherman is investigating how the helper T cells interact with these low-affinity killer T cells to make them more reactive. She is defining the rules that govern whether or not T cells see self antigen, how tolerance is established, how it is overcome, and whether there is some way to salvage it.

She has found that up-and-down fluctuations of the levels of certain cytokines -- those inflammatory chemicals that cells secrete -- prod the killer T cells to become efficient executioners of islet cells, leading to their destruction in the pancreas and to the development of diabetes in the patient.

SPECIFIC CYTOKINE CULPRITS

Sarvetnick's laboratory is looking at how various cytokines produced by islet cells and by other immune cells during viral infection of the pancreas influence the pathogenic potential of CD8 T cells in diabetes.

Recently, she demonstrated that if islet cells mount a vigorous defense against a viral infection by producing certain cytokines, then the owner of those cells is not likely to develop Type 1 diabetes. In particular, she showed that islet cells can survive the infection if they are able to detect soluble proteins called Type 1 interferons. She also showed that if they lose the ability to make this response, they disappear from the body upon infection.

"[These cytokines] can affect the half-life of T cells and the antigen presenting cells and change the way that the killer T cells get primed," Sarvetnick explains.

Sarvetnick's laboratory has already demonstrated that certain cytokines produced at certain times of infection can lead to the development or inhibition of diabetes in their models. For instance, the molecule interleukin-4 has a potent inhibitory effect on the development of diabetes in pancreas cells expressing the molecule. Another example is if the beta cells produce a chemical called interleukin-10, they have the ability to protect themselves from the virus. But the exact mechanism through which these cytokines enhance the pathogenicity of killer T cells is still unknown, as are the mechanisms through which the regulatory cytokines are themselves regulated.

THE GOAL IS THERAPY

Ultimately, the three scientists would like to understand the problems leading to Type 1 diabetes in order to be able to suggest new strategies for treatment as well as prevention.

One of the great advances that has come in the treatment of Type 1 diabetes in the last 35 years has been the pancreas transplant, which involves replacing the pancreas of a diabetes patient with a healthy organ from a donor. However, this is a major, complicated surgery, limited both by its inherent risk and the low availability of donor organs.

A better solution would be to find a way to provide people who are at risk of developing diabetes with the tools that will enable their pancreatic beta cells to defend themselves during a viral infection. Then Type 1 diabetes would become a preventable disease -- the goal of the collaboration.

"Having colleagues focused on a single goal makes the work more rewarding, productive, and fun," says Sherman. "The collaboration has worked well, and we're really proud of it."