A team led by the Wayne State University School of Medicine’s Kezhong Zhang, Ph.D., has discovered why people living in areas with higher than normal levels of air pollution are at increased risk of developing metabolic disorders such as type 2 diabetes, obesity and atherosclerosis, the thickening of artery walls.

The study pinpoints the stress mechanism that causes air pollution to impair both lipid and glucose metabolism and insulin action in the liver. The team expects the work to have a major impact on health policy decision-making, clinical disease diagnosis and treatment.

“Our study indicated that those who work under high levels of PM2.5 exposure, such as truck drivers and car industry employees, have much higher risk to developing metabolic disease, such as obesity and type 2 diabetes,” Dr. Zhang said. PM2.5 is airborne particulate matter with an aerodynamic diameter smaller than 2.5 micrometers. It’s a mix of particles and gases from gasoline and diesel engines, together with dust from roads, tires and brakes.

His team worked with other groups in the School of Medicine’s Center for Molecular Medicine and Genetics, as well as researchers at Ohio State University. Dr. Zhang, assistant professor of Molecular Medicine and Genetics and of Immunology and Microbiology, is the project’s principal investigator.

“PM2.5 particles are the major toxic components of air pollution. PM2.5 pollution has major impact on public health for the general population in urban areas, especially for those who live in areas of intensive traffic or industrial activity. Recent epidemiological studies and clinical observations suggested that populations under high levels of PM2.5 exposure have much higher risk to develop cardiovascular disease and metabolic disease,” he said.

The risk is through liver-associated inflammatory stress and metabolic impairment caused by PM2.5. Manufacturing employees, truck drivers and others experiencing long-term daily road traffic should pay close attention to blood markers or liver enzymes that indicate metabolic disease.

“According to our findings, these individuals should adjust their diets and lifestyles to reduce the risk caused by air pollution,” he said.

Dr. Zhang suggests eating a diet high in antioxidants, especially strawberries.

The researchers also recommend that physicians and other health care professionals apply preventive therapeutic strategies or health care approaches toward the liver for patients exposed to regular air pollution.

The study, “Exposure to ambient particulate matter induces a NASH-like phenotype and impairs hepatic glucose metabolism in an animal model,” was published on line at www.sciencedirect.com, and is expected to appear in the January issue of the Journal of Hepatology.

In the study, the group exposed an animal model to real-world PM2.5 in Columbus, Ohio, where most of the PM2.5 components were attributed to long-range transport and traffic. In the United States, six of the top 25 cities considered most polluted between 2007 and 2011 were in the Midwest, as reported by the American Lung Association.

“Columbus, where the animals were exposed in this study, is a ‘perfect’ site to study the adverse health effects of PM2.5, and the levels and composition of PM2.5 from Columbus is a regional representative of Midwest source of air pollution in the United States,” Dr. Zhang said.

Recent epidemiologic studies have linked air pollution to the development of type 2 diabetes. Diabetes’ prevalence in the U.S. increased with increasing airborne particulate matter PM2.5 concentrations, as evidenced by a 1 percent increase in diabetes prevalence seen with a 10 μg/m3 (micrograms per cubic meter of air) increase in PM2.5 exposure, he said.

While most researchers in the field are studying the toxic effects of PM2.5 on lung and blood vessels, Dr. Zhang’s team studied the pathological effects and stress mechanisms of PM2.5 exposure on the liver, the organ of detoxification and metabolism closely associated with the development of metabolic disease.

The work revealed that PM2.5 exposure triggers inflammatory stress responses and impairs insulin signaling in the liver, leading to key features of non-alcoholic fatty liver disease, also referred to as non-alcoholic steatohepatitis, or NASH. It affects 2 percent to 5 percent of Americans, according to an April 2012 report of the National Digestive Diseases Information Clearinghouse, a service of the National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, with an additional 10 percent to 20 percent of Americans having fat in their liver with no inflammation or disease.

Dr. Leonard Lipovich’s determination to prove genetic matter once deemed “junk” has a place in clinical medicine is bringing the Wayne State University School of Medicine to the forefront of a burgeoning field occupying genome enthusiasts in the United States, Asia and Europe.

The work, on long non-coding ribonucleic acids, or lncRNAs, could lead to new therapeutics for cancer and other diseases.

“Long non-coding RNA genes comprise half of human genes. Most medical, therapeutic work so far has focused on normal, protein-coding genes. So, we – working as part of a multinational team of scientists - have just expanded, twofold, the set of genes that can be therapeutic targets,” he said.

The publication of two groundbreaking articles highlighting results from his lab at WSU’s Center for Molecular Medicine and Genetics is pushing Dr. Lipovich, and his lab’s fellow and graduate students, into the spotlight.

“For many years people pooh-poohed our field, saying that our long non-coding RNAs are either junk, or conventional protein-coding messenger RNAs that we failed to properly understand. We now demonstrate, using an experimental approach, that they are really non-protein-coding (never translated into protein) RNAs in human cells,” said Dr. Lipovich, Ph.D., assistant professor of Molecular Medicine and Genetics and of Neurology.

Dr. Lipovich is a joint last author on a paper on whole-genome translation testing of human lncRNAs, included in the September 2012 issue of Genome Research, the genetics and genomics field’s leading peer-reviewed journal. The September issue is dedicated to the latest phase of results from the Encyclopedia of DNA Elements (ENCODE) Consortium – an international human genomics effort that succeeded the completion of 2001’s Human Genome Project.

The paper sets a new standard for how to integrate RNA data with protein data in a way that has never been done. “My lab, through its computational work here at Wayne, did a vital part of the integration, developing a method that can be used in any future studies that intersect protein and RNA data genome-wide,” Dr. Lipovich said. “Unusual, rare lncRNA-encoded proteins, such as those we found, could be the results of incorrect lncRNA processing by cells in diseased tissues, and hence a huge resource of biomarkers for diagnostics.”

“Long non-coding RNAs are emerging as a huge part of primate, including human-specific, complexity or human phenotypic uniqueness. Yet, they play a critical role in regulating the conserved part of the genome,” said Emily Wood, a WSU Molecular Medicine and Genetics doctoral candidate who served as a second author on the lncRNA translation paper.

“It’s really on the edge of what’s known,” she added, calling the lncRNA field “the wild, wild West” right now.

“There is no unified model of how lncRNAs work,” she said. “We’re really interested in therapeutics in this lab. We’re also not working on a model organism. We’re looking at the activity of the human genome in actual human tissues.”

A  National Human Genome Research Institute-funded consortium, international in scope and aided by funding from several countries in Europe and Asia, ENCODE is one of the two major collaborative groups to succeed the completion of the Human Genome Project in 2001, which gave science the ability to read nature's complete genetic blueprint for building a human being.

Abnormal translation – the unusual expression of proteins from RNAs that are not supposed to be protein templates -- clearly has the potential to emerge as a key trend in cancer and autoimmunity research soon, Dr. Lipovich said, and major genomics labs at Harvard Medical School and other top universities are working on complementary aspects of this biological problem.

WSU postdoctoral fellow Hui Jia, Ph.D., in the Lipovich Lab, and WSU Molecular Medicine and Genetics doctoral candidate Will Gundling, during his rotation in the lab last year, also contributed as co-authors of the article, titled “Long noncoding RNAs are rarely translated in two human cell lines.” Dr. Jia is a joint-first author of the paper.

“The energy in the lncRNA community is phenomenal,” Wood said. “It’s a really exciting time to be part of that community. It’s not a science that’s been around forever that we can fine tune. It’s really fun to be a student and be a part of it.”

An additional paper in September’s Genome Research co-written by Dr. Lipovich, “The GENCODE catalogue of human long non-coding RNAs: Analysis of their gene structure, evolution and expression,” presents the most authoritative reference catalog of noncoding-RNA genes ever constructed.

“It will be used by the entire international ENCODE Consortium as a foundation for functional studies linking this exciting new class of RNAs to human health and disease,” said Dr. Lipovich, a middle author on this large, international effort from ENCODE’s Analysis Working Group.

The ENCODE AWG is open to all academic, government and private sector scientists interested in participating in an open process to facilitate the comprehensive identification of the functional elements in the human genome sequence, and who agree to a variety of criteria.

In the GENCODE paper, he and his colleagues found that nearly 5,000 human lncRNAs are not conserved – meaning that there are no similar or identical sequences, in species outside of primates, to these genes. These primate-specific lncRNAs are, hence, absent in mice and other animals. This highlights the limitations of animal models, and the need to study humans to understand human disease, he said. This has major implications for the molecular basis of primate and human uniqueness – which just might be encoded in part by these new RNAs, he said.

Dr. Lipovich also is a member of the Japan-based international research consortium Functional Annotation of the Mammalian Genome, the other leading post-genomic effort. FANTOM, headquartered at the RIKEN (Japan Institute of Physical and Chemical Research) Omics Science Center in Yokohama, analyzes the mammalian transcriptome -- the complete set of all RNA molecules produced in one or a population of cells – using next-generation sequencing.

For FANTOM5, he contributes computational analysis of complex loci and lncRNA network validations. Other member institutions working with RIKEN – and WSU – on this project include Harvard, University of California at Berkeley, Sweden’s Karonlinska Institutet, The Roslin Institute at the University of Edinburgh, Scotland, and the United Kingdom’s Medical Research Council. Dr. Lipovich’s RIKEN collaboration started in 2004, when he joined FANTOM3 while a postdoctoral fellow at the Genome Institute of Singapore.

“WSU earned its ENCODE AWG membership because of the world-class computational genomics that I've been doing in my lab here since 2007 – methods and results that are valued by the FANTOM Consortium in Japan and that through FANTOM exposed us to other valuable collaborators -- such as ENCODE,” Dr. Lipovich said. The Lipovich Lab is the only laboratory in the entire State of Michigan to participate in both FANTOM and ENCODE, a prestigious distinction.