eLife's high-fat diet stimulates the bones to produce inflammatory immune cells

The findings may help explain how a high-fat diet triggers inflammation that can lead to insulin resistance, type 2 diabetes and other complications
in obese individuals.

The invasion of adipose tissue by inflammatory immune cells, known as monocytes, is a hallmark of obesity, but the cause of this harmful phenomenon is unclear
.

"We wanted to know if bone marrow tissue was an early responder to a high-fat diet, which could be a precursor to the inflammation observed in obesity," said
senior author Amira Klip, senior scientist in cell biology at SickKids and professor of pediatrics, biochemistry and physiology at the University of Toronto, Canada.

Amira Klip and his colleagues found that mice fed high-fat foods began to experience metabolic disorders throughout the body and bone marrow within three weeks
.

After a few weeks, the number of monocytes in the bone marrow changed, ranging from a decrease in a monocyte called Ly6Clow to an increase
in a monocyte called Ly6Chigh.

"These results suggest that a high-fat diet can lead to the reconstruction of bone marrow fat cells, disrupt the normal balance of monocytes, and may subsequently lead to invasive Ly6Chigh monocytes spilling into the body," Klip continued
.

The team further demonstrated that white adipose tissue can stimulate these changes, and the experiment used cell samples
from mice on a high-fat diet.

"Our study reveals how a high-fat diet triggers a cascade of inflammation in the body involving bone marrow," Klip concluded
.

Bone marrow adipocytes drive the development of tissue invasive Ly6Chigh monocytes during obesity