Ars Technica recently published a story: Immune cells tweak the body’s metabolism to help control obesity.
Obesity has reached epic proportions in the United States and is rising in other developed and developing countries as they adopt our diet and lifestyle. Autoimmune diseases, like celiac disease and multiple sclerosis, and allergies, also immune-mediated, have blossomed recently, too.
These conditions have exploded within too short of a time period to be attributable to genetic changes, so environmental factors, from synthetic pesticides to plastics to antibiotics, have been blamed for their increased prevalence. While it's probably simplistic to search for one cause to explain away both these types of modern ills, some studies are indicating that immune cells and molecules are important for regulating metabolism—and are dysregulated in obesity.
A specific type of immune cell, called Group 2 innate lymphoid cells (ILC2s), were found in white adipose tissue in mice last year. Now, they have been found in the same tissue in humans. Obese people, along with obese mice, have fewer of these cells in their fat than lean individuals do.
These cells respond to an immune signaling molecule called interleukin 33 (IL-33); that same molecule diminishes obesity by increasing caloric expenditure. This increased caloric expenditure is not due to increased physical activity or to burning more calories as more food is consumed. Instead, IL-33 just enhances the number of calories burned by normal physiological processes. Researchers figured all of this out by playing with mice deficient in IL-33 as well as those deficient in ILC2s—feeding them high fat versus regular chow, treating them with injections of IL-33, and comparing them to normal mice.
[Abstract]: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14115.html
(Score: 0) by Anonymous Coward on Saturday December 27 2014, @03:39PM
This increased caloric expenditure is not due to increased physical activity or to burning more calories as more food is consumed. Instead, IL-33 just enhances the number of calories burned by normal physiological processes.
These seem like contradictory phrases to me.
(Score: 2) by Tork on Sunday December 28 2014, @04:03AM
🏳️🌈 Proud Ally 🏳️🌈
(Score: 0) by Anonymous Coward on Sunday December 28 2014, @09:28AM
Doesn't that mean it uses more calories to run basic metabolism? Which the first sentence negated?
(Score: 2) by Joe on Saturday December 27 2014, @03:42PM
Why not just throw in an unsubstantiated claim about people blaming "synthetic pesticides" and other scare quote "chemicals" for autoimmune disease?
Of course this isn't mentioned in the Nature paper and there isn't a reference, but you don't need one when you can write that people feel it is to blame.
Is the author trying to push an agenda, forgot to add a reference, or just wanted to appeal to an audience that is fearful of things that are "synthetic" or "chemicals"?
Maybe my standards for popular scientific reporting is just too high. I just get irritated when I read something like this without a reference because I would like to read the primary literature and evaluate the claim.
/rant
- Joe
(Score: 5, Informative) by opinionated_science on Saturday December 27 2014, @05:08PM
I must say, that this article like MOST peer-reviewed articles is not so contentious. They identified a molecule not found elsewhere...
As to the pseudo-science of "synthetic chemicals" it is not such a slam dunk. The problem with ALL pseudo-science (and why it might sound convincing to the un-trained) is the arbitrary detail.
There is some very strong evidence that auto-immune diseases can be triggered by microbial or viral infection. This is not a surprise. The issue is the presentation of an epitope to the immune system that triggers an inflammation response, but then does not become part of the feedback loop. i.e. find target, make antibodies, target decreases. For infections (and this includes HIV), the immune system has evolved to ramp up rapidly in response to the concentration of epitopes with exponential efficiency. Of course, HIV is fatal because evoking an immune response propagates more HIV (transmission is via T-cell communication).
It has been hypothesised and some evidence has been presented that some infections as they evolve in the body by pure chance trigger an epitope that is sufficiently similar to a "body part". This is auto-immune behaviour and has a great deal of clinical evidence.
The "hygiene hypothesis" has some pretty good evidence that the human immune system goes through a "recognise self" phase pre-natal, and then "train environment", including the passage through the birth canal (a) and maternal antibodies transfer (via lactation) (b). Clearly (a) and (b) are not always present in all modern western births.
Put together if the immune system responds to an epitope that that by chance hits a molecular shape of the body, that is an auto-immune response. If you have a "well trained" immune system (this is arbitrary it only has to be trained for where/when you are alive...), new infections may not create a huge response and this lessens chances of a random epitope matching self.
This can definitely happen via food poisoning, the synthetic peptides are made by the microbes trying to evade our immune system.
Multiple-sclerosis has been linked to a viral infection that make peptides sufficiently close to the myelin in our nerve fibres, this triggers an immune response which probably rids the body of the virus, but not before the creation of B-cell/T-cell chains that recognise myelin as foe.
The reality is our immune system is not perfect, just good enough. Our health is not guaranteed, so do the best you can not to abuse it. The problem is not that there isn't evidence for "synthetic chemicals causing auto-immune disease", The problem is matching the molecule to the anti-body in the individual. This is a very challenging problem...
(Score: 2) by buswolley on Saturday December 27 2014, @06:17PM
Thanks for the informative +++ comment
subicular junctures
(Score: 2) by frojack on Saturday December 27 2014, @07:57PM
I think Joe was objecting to the loaded language used in TFS, which originated at ARS. Even there, it was more of a throw-away line.
I don't see any of that in the Pay-walled summary. I rather suspect (but am not willing to pay $32 to read) that the study makes no such assertions.
No, you are mistaken. I've always had this sig.
(Score: 2) by Joe on Saturday December 27 2014, @08:01PM
Let me clarify what I meant. The Ars Technica article brings up how some people blame synthetic chemicals and such for the recent spike in autoimmune disease. The Nature paper that the article references makes no mention of autoimmunity at all and the closest it gets is when it references an EAE paper for how they do their subcutaneous injections.
As for the causes of autoimmunity besides genetic predisposition, the hit-and-run model (infection by a pathogen which employs molecular mimicry that leads to a breakdown of peripheral tolerance) and the hygiene hypothesis (a lack of strong antigenic stimulation leading to hyperactive responses to benign or self-antigens) have much more evidence than "synthetic chemicals".
I have not heard of an association of C-section births or lack of breast feeding with autoimmunity. There is definitely a difference in gut bacteria between C-section (resembles skin microflora) and standard birth (closer to vaginal microflora), but I am not aware of studies showing any relationship with autoimmunity. References for either would be welcome.
- Joe
(Score: 0) by Anonymous Coward on Saturday December 27 2014, @04:05PM
Ok, I've been hitting the sauce a bit early this morning so please excuse some magical thinking.
There was a time in my life I had an easy access to marijuana. During that time, I lost about 40 lbs of weight. I don't think I had ever been that slim and fit before. Heh, I remember at that time's peak, I could even see my ab muscles. I've never before or since been able to do that. I've never been so thin and fit and… alive.
So we know that marijuana can have a positive effect on the immune system.
Now, this is where I need to stop myself. Of course I'm not saying that the drug war is responsible for the obesity epidemic. That clearly couldn't be the case. I believe that marijuana was made illegal because of the ignorance about its effects. Banning alcohol required an amendment to the Constitution. Banning marijuana just required an odd tax law.
We're just now starting to figure out the complex relationships between different microorganisms in our bodies. It would be good if we could figure out how to cure obesity and grant everyone a healthy body weight, Randian Puritanism aside.