Lee lecturer shares new approaches to public health epigenetics

When it comes to discussions involving the cause of disease, the evidence is in on the impacts of environmental exposure: 70 to 90% of diseases are attributable to environmental causes. And the public health field is putting more focus on how the human genome responds to the totality of exposure of any type over a lifetime, using technology that can potentially measure hundreds of risks from one blood-based test.

Andrea Baccarelli, Leon Hess Professor and chair of the Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, investigates molecular mechanisms as pathways linking environmental exposures to human disease. Baccarelli, whose current projects cover a range of topics including epigenomics, extracellular vesicles and small non-coding RNAs, mitochondrial DNA, and the microbiome, recently delivered the seventh annual Richard V. Lee, MD, Lectureship in Global Health, titled “Public Health Epigenetics–New Paths to Precision Medicine.”

Baccarelli’s lab uses molecular biology, machine learning and data science to find the fingerprints of chemical exposures on human cells, whether from smoking, diet or environmental pollutants.

“[Environmental exposure] changes our cells,” Baccarelli said. “The good news is that we have epigenetics to find those unique fingerprints living in our cells.” Baccarelli’s research has uncovered that cells build memories — or changes to DNA that do not depend on changes in the DNA sequence — that help them react to the environment. These chemical fingerprints, Baccarelli explained, are stored in chromosomes.

One of those epigenetic mechanisms studied by Baccarelli is DNA methylation, the simple chemical modification of cytosine, one of the four nucleotide bases in DNA. His lab measures DNA methylation using microarray technology relying on blood samples. Each sample renders 850,000 points of data that researchers can examine for DNA methylation. Of the 20,000 genes in smokers, for instance, 7,000 had DNA methylation, many more than nonsmokers had.

“Cells dramatically react to smoking to the point that 40% of the human genome is reprogrammed to cope with smoking,” Baccarelli said, adding that the biomarker of methylation in smokers and former smokers also offers insights as a predictor of lung disease.

The future of human epigenomics, he said, is in the technology and testing that could become part of routine annual bloodwork and applied similarly for lifestyle and exposure modification, as well as for diagnostics.

The School of Public Health and Health Professions established the annual Richard V. Lee, MD, Lectureship in Global Health to honor the Richard V. Lee, the late UB faculty member whose passion about international health and tropical medicine took him and graduate students on annual medical expeditions to provide care to populations in some of the most remote areas on the planet. It is coordinated by the Office of Global Health Initiatives.