Featured Research

from universities, journals, and other organizations

Immune system molecules may promote weight loss

Date:
June 5, 2014
Source:
University of California - San Francisco
Summary:
The calorie-burning triggered by cold temperatures can be achieved biochemically -- without the chill -- raising hopes for a weight-loss strategy focused on the immune system rather than the brain, according to a new study. The study results are likely to further fuel the quest to identify new ways to pharmaceutically tame obesity by targeting how much energy we burn, not just how many calories we ingest.

The calorie-burning triggered by cold temperatures can be achieved biochemically -- without the chill -- raising hopes for a weight-loss strategy focused on the immune system rather than the brain, according to a new study by UC San Francisco researchers.

The team determined that two signaling molecules secreted by cells of the immune system trigger the conversion of fat-storing white fat cells to fat-burning beige fat cells. Ajay Chawla, MD, PhD, an associate professor of medicine at the UCSF Cardiovascular Research Institute, led the study, published online June 5, 2014 in the journal Cell.

Working with mice, Chawla's team discovered that the signaling molecules, called interleukin 4 and interleukin 13, activate cells known as macrophages, which in turn drive the fat conversion. In one experiment the researchers gave interleukin 4 to fat mice, which increased beige fat mass, leading to weight loss.

The finding builds on previous work by Chawla's team, which reported in 2011 in Nature that cold activates part of the immune system, and specifically activates interleukin 4 in fat. In the new study, Chawla's team determined that both interleukin 4 and interleukin 13 recruit macrophages to fat and that the production of molecules called catecholamines by the macrophages causes the browning of white fat.

When the researchers inhibited interleukin 4 signaling in white fat, they found that the mice made less beige fat, burned less energy, and could no longer maintain normal body temperature in the cold.

The study results are likely to further fuel the quest to identify new ways to pharmaceutically tame obesity by targeting how much energy we burn, not just how many calories we ingest, according to Chawla.

"If you could increase energy expenditure by even a few percent, over a period of a year or two year you would make a big difference," he said.

The new discovery is surprising, Chawla said, because it makes it clear that this control mechanism for fat burning bypasses components of the autonomic nervous system that govern many physiological adaptations. "Nutrient and energy metabolism has largely been thought to be under the control of the brain and endocrine system," he said.

In comparison to the nervous system, the immune pathway might be more easily manipulated to increase energy expenditure, Chawla said. In fact, another study published simultaneously in Cell by researchers from the Dana-Farber Cancer Institute and Harvard Medical School reports the identification of a hormone, produced in fat tissue after cold exposure, that activates interleukin 4 and interleukin 13 to drive fat burning.

Humans and other mammals shiver to keep warm, but cold also triggers the growth of fat cells that burn fuel, instead of the fat cells that store it. Keep humans indoors at 61 degrees to 63 degrees Fahrenheit without allowing them to bundle up, and they lose weight, research shows. That's because they adapt by generating more fat-burning cells to help them keep warm.

In contrast to the power-converting mechanisms in white fat cells, the gears in the power plants within fat-burning fat cells spin inefficiently. This causes them to burn more energy and generate heat. The trigger for this accelerated fat burning is the activation within the cell's power plants -- called mitochondria -- of a protein called uncoupling protein 1 (UCP1). Cells with UCP1 are capable of heat generation and fat burning, and are known as brown fat or beige fat, depending on the tissue from which they originate. They have more mitochondria than white cells and therefore have a darker tinge.

In comparison to other mammals, ranging in size from mice to bears, until a few years ago it was widely thought that humans had little brown or beige fat and little potential to generate it.

Although Chawla and many other researchers now believe that the potential to exploit brown fat for weight loss is significant, the amount of individual variation when it comes to brown fat reserves and the potential to generate more brown fat is unclear. "We don't know what the dynamic range is," Chawla said. "It appears that women have more, that we have less as we age, and that obesity is associated with having less brown fat."

Additional UCSF study authors include postdoctoral fellows Yifu Qiu, PhD, Khoa Nguyen, PhD, and Justin Odegaard, MD, PhD; and Richard Locksley, MD, a professor of medicine and Howard Hughes Medical Institute investigator. Richard Palmiter, PhD, professor of biochemistry and Howard Hughes Medical Institute investigator at the University of Washington, also is a co-author of the study. The research was funded by the National Institutes of Health and the American Heart Association.


Story Source:

The above story is based on materials provided by University of California - San Francisco. The original article was written by Jeffrey Norris. Note: Materials may be edited for content and length.


Journal Reference:

  1. Yifu Qiu, KhoaD. Nguyen, JustinI. Odegaard, Xiaojin Cui, Xiaoyu Tian, RichardM. Locksley, RichardD. Palmiter, Ajay Chawla. Eosinophils and Type 2 Cytokine Signaling in Macrophages Orchestrate Development of Functional Beige Fat. Cell, 2014; 157 (6): 1292 DOI: 10.1016/j.cell.2014.03.066

Cite This Page:

University of California - San Francisco. "Immune system molecules may promote weight loss." ScienceDaily. ScienceDaily, 5 June 2014. <www.sciencedaily.com/releases/2014/06/140605141551.htm>.
University of California - San Francisco. (2014, June 5). Immune system molecules may promote weight loss. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2014/06/140605141551.htm
University of California - San Francisco. "Immune system molecules may promote weight loss." ScienceDaily. www.sciencedaily.com/releases/2014/06/140605141551.htm (accessed July 31, 2014).

Share This




More Health & Medicine News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Health Insurers' Profits Slide

Health Insurers' Profits Slide

Reuters - Business Video Online (July 30, 2014) Obamacare-related costs were said to be behind the profit plunge at Wellpoint and Humana, but Wellpoint sees the new exchanges boosting its earnings for the full year. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com
At Least 20 Chikungunya Cases in New Jersey

At Least 20 Chikungunya Cases in New Jersey

AP (July 30, 2014) At least 20 New Jersey residents have tested positive for chikungunya, a mosquito-borne virus that has spread through the Caribbean. (July 30) Video provided by AP
Powered by NewsLook.com
Xtreme Eating: Your Daily Caloric Intake All On One Plate

Xtreme Eating: Your Daily Caloric Intake All On One Plate

Newsy (July 30, 2014) The Center for Science in the Public Interest released its 2014 list of single meals with whopping calorie counts. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins