Exosomes as potential biomarkers of radiation exposure

Exosomes = potential biomarkers of radiation in the Read more

Before the cardiologist goes nuclear w/ stress #AHA17

Measuring troponin in CAD patients before embarking on stress testing may provide Read more

Virus hunting season open

Previously unknown viruses, identified by Winship + UCSF scientists, come from a patient with a melanoma that had metastasized to the Read more

inflammatory bowel disease

Starvation signals control intestinal inflammation in mice

Intestinal inflammation in mice can be dampened by giving them a diet restricted in amino acids, the building blocks of proteins, researchers have found. The results were published online by Nature on Wednesday, March 16.

The findings highlight an ancient connection between nutrient availability and control of inflammation. They also suggest that a low protein diet — or drugs that mimic its effects on immune cells — could be tools for the treatment of inflammatory bowel diseases, such as Crohn’s disease or ulcerative colitis.

The research team, led by Emory Vaccine Center immunologist Bali Pulendran, discovered that mice lacking the amino acid sensor GCN2 are more sensitive to the chemical irritant DSS (dextran sodium sulfate), often used to model colitis in animals. This line of research grew out of the discovery by Pulendran and colleagues that GCN2 is pivotal for induction of immunity to the yellow fever vaccine.

“It is well known that the immune system can detect and respond to pathogens, but these results highlight its capacity to sense and adapt to environmental changes, such as nutritional starvation, which cause cellular stress,” he says.

Read more

Posted on by Quinn Eastman in Immunology Leave a comment

Wound-healing intestinal bacteria: like shrubs after a forest fire

In injured mouse intestines, specific types of bacteria step forward to promote healing, Emory scientists have found. One oxygen-shy type of bacteria that grows in the wound-healing environment, Akkermansia muciniphila, has already attracted attention for its relative scarcity in both animal and human obesity.

NMicro

An intestinal wound brings bacteria (red) into contact with epithelial cells (green). The bacteria can provide signals that promote healing, if they are the right kind.

The findings emphasize how the intestinal microbiome changes locally in response to injury and even helps repair breaches. The researchers suggest that some of these microbes could be exploited as treatments for conditions such as inflammatory bowel disease.

The results were published on January 27 in Nature Microbiology. Researchers took samples of DNA from the colon tissue of mice after they underwent colon biopsies. They used DNA sequencing to determine what types of bacteria were present.

“This is a situation resembling recovery after a forest fire,” says Andrew Neish, MD, professor of pathology and laboratory medicine at Emory University School of Medicine. “Once the trees are gone, there is an orderly succession of grasses and shrubs, before the reconstitution of the mature forest. Similarly, in the damaged gut, we see that certain kinds of bacteria bloom, contribute to wound healing, and then later dissipate as the wound repairs.” Read more

Posted on by Quinn Eastman in Immunology, Uncategorized Leave a comment

Whole exome sequencing in IBD

Last year, pediatric gastroenterologist Subra Kugathasan gave an “old fashioned” grand rounds talk at Children’s Healthcare of Atlanta’s Egleston hospital, describing a family’s struggle with a multifaceted problem of autoimmunity.

Subra Kugathasan, MD

Now the Journal of Pediatric Gastroenterology and Nutrition paper, on how the genetic alteration underlying the family’s struggles was identified, is published. Kugathasan reports that the young man at the center of the paper is scheduled for allogeneic bone marrow transplant in the United States (but not in Atlanta) in the next couple months.

The list of troubles the members of the family had to deal with is long: gastrointestinal issues and food allergies, skin irritation, bacterial + yeast infections, and arthritis. The mother and her brother were affected to some degree, as well as all three of the kids (see tree diagram). The youngest brother is the “proband”, a geneticist’s term for starting point.

As determined by whole exome sequencing, the gene responsible is FOXP3, which controls the development of regulatory T cells. These are cells that restrain the rest of the immune system; if they aren’t functioning correctly, the immune system is at war with the rest of the body, like in this family.

The genetic variant identified was new — that’s why whole exome sequencing was necessary to find it. The authors conclude:

Supporting the utility of WES [whole exome sequencing] in familial clusters of atypical IBD [inflammatory bowel disease], this approach led to a definitive diagnosis in this case, resulting in a justifiable treatment strategy of allogeneic bone marrow transplantation, the treatment of choice for IPEX [Immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome].

Bone marrow transplant is a big deal; doctors are essentially wiping out the immune system then bringing it back, with several associated risks. So the decision to go ahead is not taken lightly. In general, whether bone marrow transplant — either autologous (patient donates back to self) or allogeneic (the donor is someone else) — is appropriate as a treatment for inflammatory bowel disease is still being investigated. Here, since a genetic origin is clear and there are autoimmune effects beyond the digestive system, it becomes the treatment of choice.

Posted on by Quinn Eastman in Immunology Leave a comment

Inflammatory bowel disease gene regions identified

In the largest, most comprehensive genetic analysis of childhood-onset inflammatory bowel disease (IBD), Emory and Children’s Healthcare of Atlanta gastroenterologist Subra Kugathasan, MD, and colleagues identified five new gene regions, including one involved in a biological pathway that helps drive the painful inflammation of the digestive tract that characterizes the disease.

Subra Kugathasan, MD

Subra Kugathasan, MD

IBD is a painful, chronic inflammation of the gastrointestinal tract, affecting about 2 million children and adults in the United States. Of that number, about half suffer from Crohn’s disease, which can affect any part of the GI tract, and half have ulcerative colitis, which is limited to the large intestine.

Most gene analyses of IBD have focused on adult-onset disease, but this study concentrated on childhood-onset IBD, which tends to be more severe than adult-onset disease.

Kugathasan and a team of international researchers performed a genome-wide association study on DNA from over 3,400 children and adolescents with IBD, plus nearly 12,000 genetically matched control subjects, all recruited through international collaborations in North America and Europe.

In a genome-wide association study, automated genotyping tools scan the entire human genome seeking gene variants that contribute to disease risk.

The study team identified five new gene regions that raise the risk of early-onset IBD, on chromosomes 16, 22, 10, 2 and 19. The most significant finding was at chromosome locus 16p11, which contains the IL27 gene that carries the code for a cytokine, or signaling protein, also called IL27.

Kugathasan says one strength of the current study, in addition to its large sample size, is the collaboration of many leading pediatric IBD research programs, which included Emory, The Children’s Hospital of Philadelphia, the Hospital for Sick Children of the University of Toronto; the University of Edinburgh, UK; Cedars Sinai Medical Center, Los Angeles; and the IRCCS-CSS Hospital, S. Giovanni Rotondo, Italy.

The study, “Common variants at five new loci associated with early-onset inflammatory bowel disease,” was published in the November 2009 online issue of Nature Genetics.

Learn more about Kugathasan’s work at Emory.

Posted on by adobbs in Uncategorized 1 Comment