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Sunday, July 8, 2012

Antibodies Reverse Type 1 Diabetes in New Immunotherapy Animal Study

T cells (red, green) not detected and insulin (blue) readily observed in pancreatic islets of antibody-treated (Right) versus untreated (Left) diabetic NOD mouse. (Credit: Tisch Lab, UNC)

ScienceDaily — Scientists at the University of North Carolina School of Medicine have used injections of antibodies to rapidly reverse the onset of Type I diabetes in mice genetically bred to develop the disease. Moreover, just two injections maintained disease remission indefinitely without harming the immune system.

The immune system consists of T cells that are required for maintaining immunity against different bacterial and viral pathogens. In people who develop Type 1 diabetes, "autoreactive" T cells that actively destroy beta cells are not kept in check as they are in healthy people.The findings, published online ahead of print (June 29, 2012) in the journalDiabetes, suggest for the first time that using a short course of immunotherapy may someday be of value for reversing the onset of Type I diabetes in recently diagnosed people. This form of diabetes, formerly known as insulin-dependent diabetes mellitus, is an autoimmune disease in which the body's own immune T cells target and destroy insulin-producing beta cells in the pancreas.

Senior study author Roland Tisch, PhD, professor of microbiology and immunology at UNC, said a need for effective immunotherapies also exists to treat Type 1 diabetes in people already living with the disease.

"Clinically, there have been some promising results using so-called depleting antibodies in recently diagnosed Type 1 diabetic patients, but the disease process is blocked for only a short period of time," Tisch said. "These antibodies don't discriminate between T cells normally required for maintaining immunity to disease-causing pathogens and the autoreactive T cells. Therefore T cells involved in maintaining normal immune function are also going to be depleted.

"You're getting some efficacy from immunotherapy but its only transient, it doesn't reverse the disease, and there are various complications associated with the use of these depleting antibodies."

Tisch said his UNC lab has been studying the use of certain "non-depleting antibodies." These bind to particular proteins known as CD4 and CD8 expressed by all T cells. Just as the name implies, when these non-depleting antibodies selectively bind to CD4 and CD8 they don't destroy the T cells; the overall numbers of T cells are unaffected.

With this in mind Tisch wanted to determine whether these non-depleting antibodies could have a therapeutic effect in the non-obese diabetic, or NOD mouse, an excellent model for human Type 1 diabetes.

The answer is yes. In some of the recently diagnosed NOD mice, blood sugar levels returned to normal within 48 hours of treatment. Within five days, about 80 percent of the animals had undergone diabetes remission, reversal of clinical diabetes.

"The protective effect is very rapid, and once established, is long-term," he said. "We followed the animals in excess of 400 days after the two antibody treatments, and the majority remained free of diabetes. And although the antibodies are cleared from within the animals in 2-3 weeks after treatment, the protective effect persists." The study showed that beta cells in the NOD mice had been rescued from ongoing autoimmune destruction.

In looking for the mechanism to explain how the therapy worked, the researchers found that the antibodies had a very selective effect on T cells that mediated beta cell destruction. After treatment, "all the T cells that we would normally see in the pancreas or in tissues associated with the pancreas had been purged," said Tisch. This despite the fact that the numbers of T cells found in other tissues and blood were unaffected.

The researchers also found an increase in the numbers of "immune regulatory" T cells. In the healthy individual, these regulatory T cells block autoimmunity, Tisch explained. "They protect us from the autoreactive cells that all of us have. And that's why most of us don't develop autoimmune diseases such as Type 1 diabetes."

"We've demonstrated that the use of non-depleting antibodies is very robust. We're now generating and plan to test antibodies that are specific for the human version of the CD4 and CD8 molecules."

UNC study coauthors with Tisch are first-author, Zuoan Li, (now at the University of Iowa); Ramiro Diz, Aaron Martin, Yves Maurice Morillon, Douglas E. Kline, (now at the University of Chicago); Li Li (now at Harvard Medical School); and Bo Wang.

Support for research came from the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health; and from the Juvenile Diabetes Research Foundation.

World's Fastest Camera Used to Detect Rogue Cancer Cells

Optical microscope with the world's fastest camera. (Credit: Image courtesy of University of California - Los Angeles) Science Daily — The ability to distinguish and isolate rare cells from a large population of assorted cells has become increasingly important for early disease detection and treatment monitoring.

Circulating cancer tumour cells are a perfect example. Typically, only a handful are among a billion healthy cells. Yet, they are precursors to metastasis, the spread of cancer that causes about 90 per cent of cancer mortalities. Such "rogue" cells are not limited to cancer -- they also include stem cells used for regenerative medicine and other cell types.

Unfortunately, detecting such cells is challenging. Achieving good statistical accuracy requires an automated, high-throughput instrument that can examine millions of cells reasonably quickly. Microscopes equipped with digital cameras are currently the gold standard for analyzing cells, but they are too slow to be useful for this application.

Now, a new optical microscope developed by UCLA engineers could make the tough task much easier.

"To catch these elusive cells, the camera must be able to capture and digitally process millions of images continuously at a very high frame rate," said Bahram Jalali, who holds the Northrop Grumman Endowed Opto-Electronic Chair in Electrical Engineering at the UCLA Henry Samueli School of Engineering and Applied Science. "Conventional CCD and CMOS cameras are not fast and sensitive enough. It takes time to read the data from the array of pixels, and they become less sensitive to light at high speed."

The current flow-cytometry method has high throughput, but since it relies on single-point light scattering instead of taking a picture, it is not sensitive enough to detect very rare cell types, such as those present in early-stage or pre-metastasis cancer patients.

To overcome these limitations, an interdisciplinary team of researchers led by Jalali and Dino Di Carlo, a UCLA associate professor of bioengineering with expertise in optics and high-speed electronics, microfluidics, and biotechnology, has developed a high-throughput flow-through optical microscope with the ability to detect rare cells with a sensitivity of one part per million in real-time.

This technology builds on the photonic time-stretch camera technology created by Jalali's team in 2009 to produce the world's fastest continuous-running camera.

In the latest issue of the journal Proceedings of the National Academy of Sciences, Jalali, Di Carlo, and their colleagues describe how they integrated this camera with advanced microfluidics and real-time image processing to classify cells in blood samples. The new blood-screening technology boasts a throughput of 100,000 cells per second, approximately 100 times higher than conventional imaging-based blood analyzers.

"This achievement required the integration of several cutting-edge technologies through collaborations between the departments of bioengineering and electrical engineering and the California NanoSystems Institute and adds to the significant technology infrastructure being developed at UCLA for cell-based diagnostics," Di Carlo said.

Jalali and Di Carlo are members of the California NanoSystems Institute at UCLA.

Their research demonstrates real-time identification of rare breast cancer cells in blood with a record low false-positive rate of one cell in a million. Preliminary results indicate that this new technology has the potential to quickly enable the detection of rare circulating tumor cells from a large volume of blood, opening the way for statistically accurate early detection of cancer and for monitoring the efficiency of drug and radiation therapy.

"This technology can significantly reduce errors and costs in medical diagnosis," said lead author Keisuke Goda, a UCLA program manager in electrical engineering and bioengineering.

The results were obtained by mixing cancer cells grown in a laboratory with blood in various proportions to emulate real-life patient blood.

"To further validate the clinical utility of the technology, we are currently performing clinical tests in collaboration with clinicians," said Goda, a California NanoSystems Institute member. "The technology is also potentially useful for urine analysis, water quality monitoring and related applications."

The study was funded by the U.S. Congressionally Directed Medical Research Programs (CDMRP) and by NantWorks LLC and the Burroughs Wellcome Fund.