A new neuro-immune link with obesity

16th Oct 2017

A newly discovered class of immune cells may open the door to new therapies for combatting the global obesity crisis.

Researchers investigating the role of the nervous system in fat breakdown have discovered a link between nerve cells and obesity mediated by the immune system.

The sympathetic nervous system is a division of neurons which control our unconscious actions, specifically the fight-or-flight response. A group of these neurons are known to control adipose (or fat tissue) breakdown to provide the brain and body with energy.

New research uncovers how and why these cells behave differently in obese mice – a process which may be a key target for combatting the increasing rates of obesity.

In the paper, published in the high-impact journal Nature Medicine, Dr Ana Domingos describes a new group of cells which affect the sympathetic neurons.  This new type of cell is called sympathetic neuron-associated macrophages – or SAMs for short.

In obese mice, the sympathetic neurons controlling fat breakdown had significantly more SAMs associated with them compared to others.

To understand the significance of this observation, Dr Domingos and her team carried out further research into SAMs.  They found that SAMs express a protein which is responsible for transporting the neurotransmitter noradrenaline.  They also found that SAMs increased the amount of noradrenaline taken up by the sympathetic neurons.

In addition, blocking this process - either deleting the gene that codes for the transporter protein or selectively inhibiting the sympathetic neurons - increased the breakdown of fat and promoted weight loss in mice.

A similar system has been identified in samples of human nerve cells, and researchers hope that this mechanism could be a useful therapeutic target for obesity in the future.

Read the full paper by Pirzgalska et al. in Nature Medicine here.