Advance Could Also Work Against Other Viruses
In research published online today in Science, a team of scientists describe a new therapeutic strategy to target a hidden Achilles’ heel shared by all known types of Ebola virus. Two antibodies developed with this strategy blocked the invasion of human cells by all five ebolaviruses, and one of them protected mice exposed to lethal doses of Ebola Zaire and Sudan, the two most dangerous. The team included scientists from Albert Einstein College of Medicine, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Integrated Biotherapeutics, Vanderbilt University Medical Center, and The Scripps Research Institute.
Ebola viruses cause a highly fatal disease for which no approved vaccines or treatments are available. About two dozen Ebola outbreaks have been documented since 1976, when infections first occurred in villages along the Ebola River in Africa. The largest outbreak in history—the 2014-2015 Western Africa epidemic—caused more than 11,000 deaths and infected approximately 29,000 people.
Monoclonal antibodies, which bind to and neutralize specific pathogens and toxins, have emerged as the most promising treatments for Ebola patients. A critical problem, however, is that most antibody therapies target only one specific ebolavirus. For example, the most promising experimental therapy—ZMappTM, a cocktail of three monoclonal antibodies—is specific for Ebola virus Zaire, and doesn’t work against the other two viruses (Sudan and Bundibugyo), which have both caused major outbreaks. The broad-spectrum antibodies developed by the research team represent an important advance against one of the world’s most dangerous pathogens.
Exploiting Ebola’s Achilles’ Heel
In 2011, a team that included co-senior authors Kartik Chandran, Ph.D. professor of microbiology & immunology at Einstein, and John M. Dye, Ph.D., chief of viral immunology at USAMRIID, discovered that all filoviruses (the family to which ebolaviruses and the more distantly related Marburg virus belong) have an Achilles’ heel: To infect and multiply in human cells, they must all bind to a host-cell protein called Niemann-Pick C1 (NPC1).
But capitalizing on that knowledge required a completely new approach to targeting viruses: exploiting the fact that Ebola and many other viruses must enter host cell compartments called lysosomes. Once safely inside the lysosomes, the viruses transform and expose key portions of their exterior that the research team successfully targeted using monoclonal antibodies.
To gain entry to cells, filoviruses bind to the host cell’s outer membrane via glycoproteins (proteins to which carbohydrate chains are attached) that bristle from the virus’s surface. (See illustration.) A portion of the cell membrane then surrounds the virus and pinches off, eventually developing into a lysosome—a membrane-bound, intracellular compartment filled with enzymes to digest foreign and cellular components.
Filoviruses then use the host cells’ resources to break out of their lysosomal “prisons” so they can enter the host cell’s cytoplasm to multiply. Enzymes in the lysosome slice a “cap” from the virus’s glycoproteins, unveiling a site that binds to the NPC1 embedded in the lysosome membrane. NPC1, which normally helps transport cholesterol within the cell, offers Ebola virus its only means of escaping the lysosome and multiplying. By fitting its protein “key” into the NPC1 “lock,” the virus fuses itself to the lysosome membrane. (See illustration close-up.) Now the virus can propel its RNA from the lysosome and into the cell’s cytoplasm, where it can finally replicate itself.
Penetrating an Invisibility Cloak
The research team realized that monoclonal antibodies could potentially thwart all filovirus infections by neutralizing the viral protein that binds to NPC1, or by neutralizing NPC1 itself. There was just one problem: Reflecting Ebola’s ingenuity, both targets reside only in lysosomes deep within cells—making them invisible to the immune system and shielded from attack by conventional antibodies.
Dr. Chandran, Dr. Dye and co-senior author Jonathan R. Lai, Ph.D., associate professor of biochemistry at Einstein and an expert in engineering antibodies, devised a clever “Trojan Horse” strategy for overcoming the virus’s invisibility cloak: Just as the citizens of Troy unwittingly pulled a wooden horse filled with Greek soldiers into their walled city, they tricked the viruses into carrying the means of their own destruction along with them into host cells.
To do so, the research team synthesized two types of “bispecific” antibodies, each consisting of two monoclonal antibodies combined into one molecule. One bispecific antibody was devised to neutralize the viral protein that binds to NPC1, the other to target NPC1. Both had one monoclonal antibody in common: antibody FVM09, which binds to the surface glycoproteins of all ebolaviruses while the virus is outside cells, allowing the bispecific antibodies to hitch a ride with the virus into the lysosome. FVM09 was developed by co-senior author M. Javad Aman, Ph.D. at Integrated Biotherapeutics.
Once in the lysosome, the bispecific antibodies are released from the viral surface when enzymes in the lysosome slice off the glycoprotein caps—allowing the business ends of the bispecific antibodies to swing into action.
One bispecific antibody combined FVM09 with antibody MR72, which was isolated from a human survivor of Marburg virus infection by co-senior author James E. Crowe Jr., M.D., director of the Vanderbilt Vaccine Center. MR72 targets the NPC1-binding viral protein that is unveiled by all filoviruses in lysosomes. The second bispecific antibody links FVM09 to antibody mAb-548, developed at Einstein, which zeroes in on NPC1. With one bispecific antibody targeting the “lock” (NPC1) and the other targeting the “key” (the virus’s NPC1-binding protein), both had the potential for preventing Ebola virus from interacting with NPC1 and escaping from the lysosome into the cytoplasm.
Putting Antibodies to the Test
The researchers then tested their bispecific antibodies against ebolaviruses in the lab. They initially used a harmless virus (vesicular stomatitis virus) that had been genetically engineered to display glycoproteins from all five ebolaviruses on its surface. The researchers incubated the bispecific antibodies with the Ebola-like viruses and then added the mixtures to human cells in tissue culture. Both bispecific antibodies successfully neutralized all five viruses. Work in the high-containment facilities at USAMRIID confirmed that these antibodies also blocked infection by the actual Zaire, Sudan, and Bundibugyo ebolaviruses.
Next came studies at USAMRIID to test whether the two bispecific antibodies could protect mice infected with the two most dangerous ebolaviruses, Zaire and Sudan. Researchers, led by Dr. Dye, administered the bispecific antibodies two days after mice were exposed to a lethal dose of virus.
The bispecific antibody that targeted the viral binding protein provided good protection to mice exposed to both viruses. As expected, the bispecific antibody that targeted NPC1 did not protect mice. It was designed to bind specifically to human NPC1, which differs slightly in structure from the NPC1 protein found in mice.
As a next step, both bispecific antibodies will need to be tested in nonhuman primates, the current gold standard for anti-Ebola therapeutics.
The eye’s lacrimal gland is small but mighty. This gland produces moisture needed to heal eye injuries and clear out harmful dust, bacteria and other invaders.
If the lacrimal gland is injured or damaged by aging, pollution or even certain pharmaceutical drugs, a person can experience a debilitating condition called aqueous deficiency dry eye (ADDE)—sometimes called “painful blindness.”
Now a new study in animal models, led by scientists at The Scripps Research Institute (TSRI), suggests that lacrimal glands can be repaired by injecting a kind of regenerative “progenitor” cell.
“This is the first step in developing future therapies for the lacrimal gland,” said TSRI biologist Helen Makarenkova, who led the study.
The findings were published this week in the online Early Edition of the journal Stem Cells Translational Medicine.
Up for the Challenge
If injured, a healthy lacrimal gland naturally regenerates itself in about seven days. When diseased and chronically inflamed, however, regeneration stops—and scientists are not sure why.
In the new study, Makarenkova and her colleagues looked at whether they could kick start regeneration by injecting progenitor cells into the lobes that make up the lacrimal gland. Progenitor cells are similar to stem cells in their ability to differentiate into different kinds of tissue. In this study, the researchers used progenitor cells that were poised to become epithelial tissue, a key component of the lacrimal gland.
The researchers knew they faced a major challenge: sorting and separating “sticky” epithelial cell progenitors without destroying them.
“We had to figure out how to dissociate the tissue into single cells without completely obliterating everything,” said Anastasia Gromova, the study’s first author, now a graduate student at the University of California, San Diego, who spearheaded the project while interning at TSRI during her undergraduate years.
The researchers solved this problem by developing markers to label the cells of interest and then testing different enzymes and other reagents to draw them out of tissues.
Restoring Eye Health
With these cells in hand, the researchers injected them into the lacrimal glands of mouse models of Sjogren’s syndrome, an autoimmune disease that results in ADDE, dry mouth and other symptoms. The team used only older, female mice because ADDE most commonly strikes that demographic in humans.
The treated mice showed a significant increase in tear production, indicating—for the first time—that epithelial cell progenitors could repair the lacrimal gland. Further tests suggested that epithelial cell progenitors helped by restoring the connection between cells called myoepithelial contractile cells and the lacrimal gland’s secretory cells, which produce tears.
The next step in this research will be to study how long the improvement in the lacrimal gland lasts after progenitor cell injections. Makarenkova said the eventual goal is to develop therapies to boost a patient’s own regenerative abilities.
In addition to Makarenkova and Gromova, authors of the study, “Lacrimal Gland Repair Using Progenitor Cells,” were Dmitry A. Voronov of TSRI, the Russian Academy of Sciences and the A.N. Belozersky Institute of Physico-Chemical Biology of the Lomonosov Moscow State University; Miya Yoshida and Suharika Thotakura of TSRI; Robyn Meech of Flinders University; and Darlene A. Dartt of the Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard Medical School.
TSRI Study Points Way to Better Vaccines and New Autoimmune Therapies
A new international collaboration involving scientists at The Scripps Research Institute (TSRI) opens a door to influencing the immune system, which would be useful to boost the effectiveness of vaccines or to counter autoimmune diseases such as lupus and rheumatoid arthritis.
The research, published August 1, 2016, in The Journal of Experimental Medicine, focused on a molecule called microRNA-155 (miR-155), a key player in the immune system’s production of disease-fighting antibodies.
“It’s very exciting to see exactly how this molecule works in the body,” said TSRI Associate Professor Changchun Xiao, who co-led the study with Professor Wen-Hsien Liu of Xiamen University in Fuijan province, China.
An Immune System Tango
Our cells rely on molecules called microRNAs (miRNAs) as a sort of “dimmer switches” to carefully regulate protein levels and combat disease.
“People know miRNAs are involved in immune response, but they don’t know which miRNAs and how exactly,” explained TSRI Research Associate Zhe Huang, study co-first author with Liu and Seung Goo Kang of TSRI and Kangwon National University.
In the new study, the researchers focused on the roles of miRNAs during the critical period when the immune system first detects “invaders” such as viruses or bacteria. At this time, cells called T follicular helpers proliferate and migrate to a different area of the lymph organs to interact with B cells.
“They do a sort of tango,” said Xiao.
This interaction prompts B cells to mature and produce effective antibodies, eventually offering long-term protection against infection.
“The next time you encounter that virus, for example, the body can respond quickly,” said Xiao.
Identifying a Dancer
Using a technique called deep sequencing, the team identified miR-155 as a potential part of this process. Studies in mouse models suggested that miR-155 works by repressing a protein called Peli1. This leaves a molecule called c-Rel free to jump in and promote normal T cell proliferation.
This finding could help scientists improve current vaccines. While vaccines are life-saving, some vaccines wear off after a decade or only cover around 80 percent of those vaccinated.
“If you could increase T cell proliferation using a molecule that mimics miR-155, maybe you could boost that to 90 to 95 percent,” said Xiao. He also sees potential for using miR-155 to help in creating longer-lasting vaccines.
The research may also apply to treating autoimmune diseases, which occur when antibodies mistakenly attack the body’s own tissues. Xiao and his colleagues think an mRNA inhibitor could dial back miR-155’s response when T cell proliferation and antibody production is in overdrive.
For the next stage of this research, Xiao plans to collaborate with scientists on the Florida campus of TSRI to test possible miRNA inhibitors against autoimmune disease.
In a new study, scientists at The Scripps Research Institute (TSRI) have identified drug candidates through transcriptional profiling that can boost a cell’s ability to catch the “typos” in protein production that can cause a deadly disease called amyloidosis.
“This study reveals a new approach to intervene in human disease,” said Luke Wiseman, assistant professor at TSRI and co-senior author of the new research with Jeffery Kelly, Lita Annenberg Hazen Professor of Chemistry at TSRI.
There are lessons to be learned from venoms.
Scorpions, snakes, snails, frogs and other creatures are thought to produce tens or even hundreds of millions of distinct venoms. These venoms have been honed to strike specific targets in the body.
For victims of a scorpion’s sting, that spells doom. For scientists, however, the potent molecules in venoms hold the potential to be adapted into medicines. But venoms are difficult to isolate and analyze using traditional methods, so only a handful have been turned into drugs.
Now a team led by scientists at The Scripps Research Institute (TSRI) has invented a method for rapidly identifying venoms that strike a specific target in the body—and optimizing such venoms for therapeutic use.
The researchers demonstrated the new method by using it to identify venoms that block a certain protein on T cells—a protein implicated in multiple sclerosis, rheumatoid arthritis and other inflammatory disorders. The researchers then used their method to find an optimized, long-acting variant of a venom that blocks this protein and showed that the new molecule powerfully reduces inflammation in mice.
“Until now we haven’t had a way to seriously harness venoms’ vast therapeutic potential,” said principal investigator Richard A. Lerner, Lita Annenberg Hazen Professor of Immunochemistry at TSRI.
The report on the advance by Lerner and his colleagues was selected as a “Hot Paper” and cover story by the journal Angewandte Chemie.
Choose Your Poison
The use of venoms as therapies may seem paradoxical, since these molecules generally evolved to harm and kill other organisms. But a low dose delivered to the right place can sometimes have highly beneficial effects. The pain-killing drug ziconotide (Prialt®), for example, is derived from one of the venoms used by cone-snails to immobilize their fishy prey. Venoms also are attractive from a drug development perspective because they tend to hit their targets on cells with very high potency and selectivity.
Findings Reveal Human Proteins Are Better Drug Targets than Previously Thought
Scientists at The Scripps Research Institute (TSRI) have developed a powerful new method for finding drug candidates that bind to specific proteins.
The new method, reported in this week’s issue of Nature, is a significant advance because it can be applied to a large set of proteins at once, even to the thousands of distinct proteins directly in their native cellular environment. The TSRI researchers demonstrated the technique to find “ligands” (binding partners) for many proteins previously thought to bind poorly to small molecules that can be used to determine the functions of their protein targets and can serve as starting compounds for the development of drugs.
Among the newly discovered ligands are selective inhibitors of two caspase enzymes, which have key roles in multiple diseases but have largely eluded efforts to target them with drugs.
“Our data suggest that the human proteome is much more broadly targetable with small molecules than has been previously appreciated,” said principal investigator Benjamin F. Cravatt, chair of the Department of Chemical Physiology and member of the Dorris Neuroscience Center and Skaggs Institute for Chemical Biology at TSRI. “That opens up new possibilities for developing scientific probes and ultimately drugs.”
The Scripps Research Institute (TSRI) is a nonprofit American medical research facility that focuses on research and education in the biomedical sciences.
Headquartered in San Diego, California with a sister facility in Jupiter, Florida, the institute is home to 3,000 scientists, technicians, graduate students, and administrative and other staff, making it among the largest private, non-profit biomedical research organizations in the world.
TSRI’s California campus is located on 35 acres (140,000 m2) of land between the Torrey Pines State Reserve and the University of California, San Diego in La Jolla. In Florida, TSRI occupies 30 acres (120,000 m2) adjacent to the John D. MacArthur campus of Florida Atlantic University in Palm Beach County, Florida.
The Florida campus of TSRI operates a 350,000-square-foot (33,000 m2) state-of-the-art biomedical research facility focusing on neuroscience, cancer biology, medicinal chemistry, drug discovery, biotechnology, and alternative energy development. Approximately 450 faculty, staff and students occupy TSRI’s Florida campus. TSRI Florida is housed on the Jupiter campus of Florida Atlantic University.
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- New Method Enlists Electricity for Easier, Cheaper, Safer Chemistry – May 11, 2016
- A Cheap, Portable Drug-Discovery System: LIGHTSABR – February 14, 2016
- Scripps Florida Scientists Reveal Potential Treatment for Life-Threatening Viral Infections – November 25, 2015
- Cancer Treatment Breakthrough: Researchers Engineer A Way To Make Leukemia Cells Kill Each Other – October 23, 2015
- Progress towards a universal, and perhaps, lifelong flu vaccine – August 30, 2015
- Scripps Research, Mayo Clinic Scientists Find New Class of Drugs that Dramatically Increases Healthy Lifespan – March 10, 2015
- Scientists Announce Anti-HIV Agent So Powerful It Can Work in a Vaccine – February 19, 2015
- Scientists Open New Frontier of Vast Chemical ‘Space’ – December 21, 2014
- Scripps Florida Scientists Make Diseased Cells Synthesize Their Own Drug – September 6, 2014
- Scripps Research Institute Chemists Uncover Powerful New Click Chemistry Reactivity – August 18, 2014
- Scientists Add Letters to DNA’s Alphabet, Raising Hope and Fear | synthetic biology – May 8, 2014
- Scripps Research Institute Scientists Create First Living Organism that Transmits Added Letters in DNA ‘Alphabet’ | DNA biology – May 7, 2014
- Scientists find new way to upgrade natural gas
- Scripps Research Institute Scientists Identify First Potentially Effective Therapy for Human Prion Disease
- Innovative Screening Strategy Swiftly Uncovers New Drug Candidates, New Biology | drug-discovery strategy
- Clinical Trial Indicates Gabapentin Is Safe and Effective for Treating Alcohol Dependence
- New Strategy to Treat Multiple Sclerosis Shows Promise in Mice
- Scripps Florida Scientists Identify Potential New Drug for Inherited Cancer
- Drug Candidate Leads to Improved Endurance
- New Drug Candidate Has Dramatic Effect on Endurance
- New Compound Excels at Killing Persistent and Drug-Resistant Tuberculosis
- Chemists Invent Powerful Toolkit, Accelerating Creation of Potential New Drugs
- Meth Vaccine Shows Promising Results in Early Tests
- New ‘Biopsy in a Blood Test’ to Detect Cancer
- Discovery May Lead to Safer Treatments for Asthma, Allergies and Arthritis
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Carbon-Carbon Coupling Made Easy
Scientists at The Scripps Research Institute (TSRI) have devised a new molecule-building method that is likely to have a major impact on the pharmaceutical industry and many other chemistry-based enterprises.
The method, published as an online First Release paper in Science on April 21, 2016, allows chemists to construct novel, complex and potentially very valuable molecules, starting from a large class of compounds known as carboxylic acids, which are relatively cheap and non-toxic. Carboxylic acids include the amino acids that make proteins, fatty acids found in animals and plants, citric acid, acetic acid (vinegar) and many other substances that are already produced in industrial quantities.
“This is one of the most useful methods we have ever worked with, and it mostly involves materials that every chemist has access to already, so I think the interest in it will expand rapidly,” said principal investigator Phil S. Baran, Darlene Shiley Professor of Chemistry at TSRI.
“This exciting new discovery represents a significant advance in our ability to transform simple organic molecules and to rapidly build complex structures from readily available materials—we expect to use it in both the discovery and development of biologically active compounds that help patients prevail over serious disease,” said co-author Martin D. Eastgate, a Director in Chemical and Synthetic Development at Bristol-Myers Squibb, who participated in the study as part of a long-standing research collaboration between Bristol-Myers Squibb and TSRI.
A new study led by scientists at The Scripps Research Institute (TSRI) reveals a previously unknown type of immune cell. The discovery opens new avenues in the effort to develop novel therapies for autoimmune diseases such as type 1 diabetes.
The newly discovered cells resemble conventional T cells, yet are biased toward becoming T regulatory cells (Tregs), which protect the body from autoimmune disease.
“This study was eye-opening,” said study senior author and TSRI biologist Oktay Kirak. “You wouldn’t expect these cells to have this ability. The best analogy I have is Clark Kent turning into Superman. Clark Kent looks like an Average Joe, so no one would expect him to have the same abilities as Superman.”
Stopping Type 1 Diabetes
The body has an army of millions of immune cells. These cells contain receptors generated through random genetic rearrangements–a clever strategy to keep them ready to fight unfamiliar viruses and bacteria. This diverse pool leaves many questions for scientists, however, about which ones are active in specific diseases.
One puzzling disease is type 1 diabetes, in which immune cells mistakenly attack insulin-producing cells in the pancreas. Scientists know that Tregs should be able control this autoimmune response, deflecting the attack. Current clinical trials are focusing on increasing the numbers of Treg cells and finding ways to make them enter the pancreas.
In the new study, researchers began to solve this problem by isolating an individual Treg from a mouse model of type 1 diabetes and inserting its nucleus–which contained the unique genetic immune receptor information–into a mouse egg cell that had its own nucleus removed.
Using this cloning method (Somatic Cell Nuclear Transfer), the scientists created a mouse model that produced only the original Treg, allowing them to study its origins and functions for the first time.