Targeting fatty acids may be treatment strategy for arthritis, leukemia

The bone marrow of mice with normal ether lipid production (top) contains more white blood cells than are found in the bone marrow of mice with ether lipid deficiency (bottom).
Credit: Washington University School of Medicine

Enzymes linked to diabetes and obesity appear to play key roles in arthritis and leukemia, potentially opening up new avenues for treating these diverse diseases, according to new research at Washington University School of Medicine in St. Louis.

Working with genetically engineered mice, the researchers discovered that the same enzymes involved in turning carbohydrates into the building blocks of fats also influence the health of specialized white blood cells called neutrophils. Neutrophils are the most abundant type of white blood cell and a hallmark of inflammation, which is a key component of rheumatoid arthritis. Abnormally high levels of neutrophils also are common in patients with leukemia.

The study is published Jan. 6 in the journal Cell Metabolism.

"The link between these enzymes and neutrophils was a big surprise," said first author Irfan J. Lodhi, PhD, assistant professor of medicine. "We had never thought about treating rheumatoid arthritis or leukemia by targeting enzymes that produce fatty acids, but this work supports that line of thinking."

In the study, mice that couldn't make enzymes needed to produce a certain type of fat abruptly lost weight and developed extremely low white blood cell counts, with very few neutrophils. Without this fat, called an ether lipid, neutrophils died.

That discovery could lead to the targeting of ether lipids as a way to reduce the number of neutrophils in inflammatory diseases and leukemias. The researchers believe limiting, rather than eliminating, ether lipids may be the best approach because neutrophils are important infection fighters.

"This may be a pathway to limit inflammation," said senior investigator Clay F. Semenkovich, MD, the Herbert S. Gasser Professor of Medicine. "If we could reduce the activity of these enzymes without eliminating them entirely, it could lower the levels of ether lipids and potentially help patients with leukemia and inflammatory diseases such as arthritis."

Semenkovich, also a professor of cell biology and physiology and director of the Division of Endocrinology, Metabolism and Lipid Research, said the enzymes specifically target neutrophils without affecting other immune cells.

"So ether lipids appear to be a very precise target," he said.

Working with Daniel Link, MD, the Alan A. and Edith L. Wolff Distinguished Professor of Medicine, the researchers learned that inactivating the enzymes didn't harm the precursors of neutrophils; only mature neutrophils were killed.

That could mean strategies to limit the production of ether lipids might lower neutrophil levels only temporarily so that when treatment stops, a patient's neutrophil count gradually would rise, allowing the immune system to return to normal.

Source: Washington University in St. Louis

Special delivery: Hitchhiking microparticles deliver drugs directly

Disc-shaped microparticles use monocytes to get to their destination. Credit: Peter Allen illustration

Inflammation is a normal and often beneficial response to injury or infection. The swelling, heat and even pain are the body's attempts to protect its soft tissue, remove offending objects, substances or microbes and initiate healing. However, persistent inflammation is often indicative of more serious conditions and can lead to problems of its own, including impaired healing, loss of function or even tissue death.

"Many diseases result in inflammation," said Samir Mitragotri, professor of chemical engineering at UC Santa Barbara and director of the campus's Center for Bioengineering. Whether inflammation is a byproduct of the disease or the inflammation is the disease, it is a common indicator of a problem with the system. "If we could target the common denominator, whether the inflammation is coming from cancer or arthritis, we could deliver the drug there," said Mitragotri, who specializes in targeted drug delivery.

By taking advantage of natural body processes, researchers at UC Santa Barbara and MIT have developed a method of targeting inflamed tissues, creating a way to treat both the inflammation and its underlying cause.

"It's a cell-mediated approach to targeted drug delivery," said UCSB grad student researcher Aaron Anselmo, lead author of a study in the current issue of the Journal of Controlled Release.

Key to this technology is the utilization of monocytes, the type of white blood cell known for its ability to penetrate into deep sections of tissue. Under normal circumstances, the job of these monocytes is to circulate in the blood and respond to biochemical signals that indicate inflammation -- a sign of injury or infection. Once at the site, these monocytes transform into macrophages, cells that reside in the affected tissues to engulf and digest foreign material.

Working with the expertise of chemical engineering and materials science researchers at MIT, including graduate researcher Jonathan Gilbert and professors Robert Cohen and Michael Rubner, the UCSB researchers developed an approach based on "cellular backpacks" -- flat, disc-shaped polymeric particles that could, in the near future, hold therapeutic agents that can be released at the site of the inflammation. These polymeric discs are coated on one side with a single layer of an antibody that can bind to receptors on the monocyte's surface.

To prevent the cellular backpack from being engulfed and devoured by the very cell that is transporting it, the researchers chose a flexible particle that is nonspherical in shape, which, according to the study, has proved to be more durable and resistant to phagocytosis than a rigid spherical particle. The shape and flexibility gives the backpack the ability to bind strongly while resisting phagocytosis to hitchhike onto monocytes and reach the inflamed tissue.

In-vitro and in-vivo tests have proved that cellular backpacks are successful in attaching to and being transported by monocytes to target areas without impairing the monocytes' natural functions, said Anselmo. Further studies will include research into how much drug can be loaded into the cellular backpacks. Ideally, Anselmo said, the cellular backpacks loaded with drugs would be injected into the bloodstream, whereupon they would attach to these traveling monocytes and hitchhike to the target region. At the inflamed site, the particles would simultaneously degrade and release their drugs.

The development of effective cellular backpacks has broad potential, say the researchers.
"Basically the main benefit is that you can deliver the drug in a more effective dose," Mitragotri said. Take for example the case of chemotherapy, which often has a narrow therapeutic range: Too little and the treatment is not effective, too much and it can be lethal. 
Because chemo travels through the bloodstream and affects all the tissues it comes in contact with, dosages are restricted at least in part based on the deleterious effect it has on other, unafflicted organs and their functions. Not only can targeted therapy ensure other body systems remain unaffected, Mitragotri explained, but it could allow for higher doses of drug to the site, which could decrease treatment time.

Source: University of California - Santa Barbara

Small, fast, and crowded: Mammal traits amplify tick-borne illness

Chipmunks are small-bodied animals with fast lives and dense populations. When ticks feed on them, they are more likely to pick up multiple disease-causing pathogens. Credit: © dwags / Fotolia

In the U.S., some 300,000 people are diagnosed with Lyme disease annually. Thousands also suffer from babesiosis and anaplasmosis, tick-borne ailments that can occur alone or as co-infections with Lyme disease. According to a new paper published in PLOS ONE, when small, fast-living mammals abound, so too does our risk of getting sick.

In eastern and central North America, blacklegged ticks are the primary vectors for Lyme disease, babesiosis, and anaplasmosis. The pathogens that cause these illnesses are widespread in nature; ticks acquire them when they feed on infected animals.

Richard S. Ostfeld, the paper's lead author and a scientist at the Cary Institute of Ecosystem Studies, has researched the ecology of Lyme disease since 1992. "A pattern emerged in our long-term studies. Ticks that fed on certain rodents and shrews were much more likely to pick up multiple pathogens, making the environment riskier for people."

To investigate why mammals differ in their 'reservoir competence' or ability to transmit pathogens to ticks, Ostfeld and his co-authors from Bard College, Oregon State University, the University of South Florida, and EcoHealth Alliance took a two-pronged approach.

First, they looked at life history traits for nine mammals known to harbor Lyme disease, babesiosis, and anaplasmosis. Attributes like body size, litter size, and life span were taken into consideration.

Then they looked at the role of mammal population density. As 'sit and wait' parasites, ticks are much more likely to encounter animals with dense populations. This, in turn, could help pathogens evolve to exploit specific hosts, resulting in more effective transmission rates.

For Lyme disease and anaplasmosis, fast life history features were a strong predictor of an animal's ability to transmit infection to ticks. Body size was inversely related to reservoir competence. Raccoon, skunk, opossum, squirrel, and deer infected fewer ticks than their mouse, chipmunk, and shrew counterparts.

Ostfeld notes, "This is consistent with past research on Lyme disease, West Nile virus, and Eastern Equine encephalitis. There is evidence that animals that mature early and have frequent, large litters invest less in some immune defenses, making them better pathogen hosts."

Population density was the best predictor of species' abilities to transmit all three pathogen groups, with animals that ticks encountered most frequently being the most effective at transferring infection. Co-author Felicia Keesing of Bard College explains, "Fast life history and high population density often go hand-in-hand. In rodents and shrews, pathogen adaptation and poor immune defense may be working together to amplify disease spread."

With Ostfeld concluding, "In our struggle to manage the ever-growing list of tick-borne diseases, we need to understand which animals magnify human disease risk. Our results suggest when generalist pathogens emerge, small mammals with large populations and a fast pace of life warrant careful monitoring."

Source: Cary Institute of Ecosystem Studies

New natural supplement relieves canine arthritis

Portrait old dog

Arthritis pain in dogs can be relieved, with no side effects, by a new product based on medicinal plants and dietary supplements that was developed at the University of Montreal's Faculty of Veterinary Medicine. "While acupuncture and electrical stimulation are two approaches that have been shown to have positive effects on dogs, until now a few studies have investigated a plant-based approach to therapy," explained Professor Éric Troncy, senior author of the study. His findings were published in Research in Veterinary Science.

Troncy and his team worked with 32 dogs (and their owners!) who had been diagnosed with arthritis by X-ray and orthopaedic exam, and who all weighed more than 20 kilograms. By drawing on existing rodent studies and working with Pierre Haddad of the university's Department of Pharmacology, Troncy developed two formulas for his trial. These formulas are not currently commercially available.

The first formula, composed of curcumin, devil's claw, black current, Indian frankincense (Salai), willow bark, pineapple bromelaine and camomile, was developed to treat arthritis-induced inflammation. The second included the same ingredients, plus dietary supplements such as omega 3, chondroitin sulfate and glutamine, and was formulated in the hope that it would promote the regeneration of articulations.

Half the dogs received the first formula for four weeks and then the second formula for another four weeks. The other half, acting as the control, received a placebo. The outcomes were tested using three methods. Firstly, the dogs were filmed as they walked at a consistent speed over a special platform that captures the strength of each paw. Secondly, a special electronic collar recorded the dogs' daily activities. And finally, the owners were asked to provide their own evaluations of their dog's behaviour.

The researchers were able to identify an improvement by the fourth week of the trial. "After the eight week course, on average, the strength of the dogs receiving treatment had improved to the equivalent of a kilo of extra strength per paw, which is moreover. None of these dogs saw their health decline, unlike 35.8% of the dogs who were given the placebo," said Maxim Moreau, who was first author of the study.

The improvements were also reflected in the dogs' daily lives. The collars revealed that the dogs receiving treatment maintained their physical activity, and in fact the group average increased from six hours of daily activity to eight. Meanwhile, the dogs receiving the placebo were progressively less active. "In some cases, we recorded the dogs to ensure that the collar was recording actual physical activity rather than movements such as scratching," Troncy explained.

Nonetheless, the ratings from the owners were more mixed. "This third evaluation was more subjective and the contrast between the test group and the control group less stark," Troncy said. "We suspect that the owner may have forgotten what the animal's behaviour was like before it developed arthritis."

The findings raise the possibility of offering a new form of treatment to human beings. "The model of evaluation that we have used is the best for predicting the efficacy of anti-arthritis treatments. We can therefore consider that clinical trials on humans would have a good chance of having positive outcomes," Troncy said.

About this study: This study was funded in part by a grant from ArthroLab Inc., an ongoing New Opportunities Fund grant (#9483) and a Leader Opportunity Fund grant (#24601) from the Canada Foundation for Innovation for the pain/function equipment, a Discovery Grant (#327158-2008; #441651-2013) from the Natural Sciences and Engineering Research Council of Canada for the bio-analyses and salaries, and by the Osteoarthritis Chair of the University of Montreal Hospital Centre, Université de Montréal. Maxim Moreau received a doctoral scholarship from the Canadian Institutes of Health Research (TGF-53914) -- Strategic Training Initiative in Health Research program (MENTOR) and a doctoral scholarship from the Fonds de recherche du Québec-Santé.

Source: Universite de Montreal

Making lab-grown tissues stronger

Connective tissues like cartilage are made of cross-linked bundles of collagen fibers. UC Davis biomedical engineers have discovered that reducing oxygen or adding an enzyme called LOX can make these bundles stronger. The technique can be used to strengthen both natural cartilage kept in the lab for transplant, and artificial cartilage grown in culture. Credit: Eleftherios Makris and Kyriacos Athanasiou, UC Davis

Lab-grown tissues could one day provide new treatments for injuries and damage to the joints, including articular cartilage, tendons and ligaments.

Cartilage, for example, is a hard material that caps the ends of bones and allows joints to work smoothly. UC Davis biomedical engineers, exploring ways to toughen up engineered cartilage and keep natural tissues strong outside the body, report new developments this week in the journal Proceedings of the National Academy of Sciences.

"The problem with engineered tissue is that the mechanical properties are far from those of native tissue," said Eleftherios Makris, a postdoctoral researcher at the UC Davis Department of Biomedical Engineering and first author on the paper. Makris is working under the supervision of Professor Kyriacos A. Athanasiou, a distinguished professor of biomedical engineering and orthopedic surgery, and chair of the Department of Biomedical Engineering.

While engineered cartilage has yet to be tested or approved for use in humans, a current method for treating serious joint problems is with transplants of native cartilage. But it is well known that this method is not sufficient as a long-term clinical solution, Makris said.
The major component of cartilage is a protein called collagen, which also provides strength and flexibility to the majority of our tissues, including ligaments, tendons, skin and bones. Collagen is produced by the cells and made up of long fibers that can be cross-linked together.

Engineering new cartilage

Researchers in the Athanasiou group have been maintaining native cartilage in the lab and culturing cartilage cells, or chondrocytes, to produce engineered cartilage.

"In engineered tissues the cells produce initially an immature matrix, and the maturation process makes it tougher," Makris said.

Knee joints are normally low in oxygen, so the researchers looked at the effect of depriving native or engineered cartilage of oxygen. In both cases, low oxygen led to more cross-linking and stronger material. They also found that an enzyme called lysyl oxidase, which is triggered by low oxygen levels, promoted cross-linking and made the material stronger.

"The ramifications of the work presented in the PNAS paper are tremendous with respect to tissue grafts used in surgery, as well as new tissues fabricated using the principles of tissue engineering," Athanasiou said. Grafts such as cadaveric cartilage, tendons or ligaments -- notorious for losing their mechanical characteristics in storage -- can now be treated with the processes developed at UC Davis to make them stronger and fully functional, he said.
Athanasiou also envisions that many tissue engineering methods will now be altered to take advantage of this strengthening technique.

Source: University of California - Davis