Some obese people may be able to remain metabolically healthy despite their size because their bodies produce low levels of a certain molecule, according to a study published today in the journal Cell.
High levels of the molecule, called heme oxygenase-1 or HO-1, are linked to metabolic illnesses such as diabetes and heart disease, as well as high blood pressure, blood sugar and cholesterol, which lead to these diseases.
Early tests in mice show that blocking HO-1 can improve metabolic healthiness. This suggests a potential new strategy for treating obesity-related disease.
Past research has estimated 25-30% of obese people have no metabolic illnesses or risk factors. But the reasons were unknown.
So the research team from the Medical University of Vienna and the Max Planck Institute of Immunobiology and Epigenetics in Freiburg, Germany, set out to investigate whether HO-1 was responsible.
In studies of human tissue, they found higher levels of HO-1 in liver and fat biopsies from people who were obese and insulin-resistant compared with obese people who were metabolically healthy.
Using mouse models, the researchers then deleted the HO-1 gene in immune cells called macrophages. This left the mice with better liver function and an increase in insulin sensitivity, indicating improved metabolic health.
As one of the strongest predictors of unhealthy obesity, the researchers said the HO-1 molecule was now a candidate biomarker for identifying metabolically unhealthy obese people to detect the onset of disease.
“This could allow clinicians to use targeted interventions to prevent disease progression specifically in obese individuals who show early signs of type 2 diabetes,“ senior study author J. Andrew Pospisilik, from the Max Planck Institute, told Cell.