Fat Beneath Skin May Ward Off Infections

By Dr. Mercola

When you get a cut or a scratch, what keeps invading bacteria from making you sick? Specialized immune-system cells called neutrophils and monocytes ultimately arrive at the scene, gobbling up pathogens.

In the meantime, in order to keep disease-causing microbes from multiplying out of control, other cell types in the area of the wound, including mast cells and leukocytes, provide a more immediate response against invaders.

It turns out, however, that these are not your body's only line of defense. Your body's dermal fat cells, or adipocytes – the ones just below your skin – may be the first responders against potential invaders.

Skin Fat Might Protect You from Infections

The fat underneath your skin is known to help insulate your body, protecting you from extreme temperatures. It also helps attach the dermis layer of your skin to your muscles and bones, the latter of which it also helps pad in the event of a fall.1

But fat cells do far more than control your body temperature and act as storage for energy… they also fight infections, according to a new study.2 Richard Gallo, MD, PhD, professor and chief of dermatology at UC San Diego School of Medicine, the study's lead researcher, said:3

"It was thought that once the skin barrier was broken, it was entirely the responsibility of circulating (white) blood cells like neutrophils and macrophages to protect us from getting sepsis," said Gallo, the study's principal investigator.

"But it takes time to recruit these cells (to the wound site). We now show that the fat stem cells are responsible for protecting us. That was totally unexpected. It was not known that adipocytes could produce antimicrobials, let alone that they make almost as much as a neutrophil."

Fat Cells Produce Germ-Fighting Antimicrobial Peptides

Previous research by Gallo and colleagues found that the pathogenic Staphylococcus aureus bacteria could be found in the fat layers of the skin,4 but they weren't sure if it played a role in infection.

The current study revealed fat layers in the skin of mice thickened after being introduced to the S. aureus bacteria. Mice that were incapable of forming new fat cells were more prone to infection. And, according to the study:5

"The differentiating fat cells secreted a small-molecule peptide called cathelicidin, specifically in response to the infection."

In other words, the fat cells produced high levels of an antimicrobial peptide (AMP) called cathelicidin antimicrobial peptide, or CAMP. AMPs are used by your body's innate immune response to kill invading pathogens, including bacteria, viruses, fungi and other pathogens.6

Further tests showed that human fat cells also produced CAMP, which suggests the animal findings will hold true in humans as well – and your fat may serve as an important germ-fighting barrier against infection.

Too Much CAMP Is Pro-Inflammatory

Antimicrobial peptides destroy the cell walls of bacteria, fungi, and viruses, making them very useful for fighting infections. You skin also produces AMPs,7and having them in your fat layer would seem to provide another layer of protection to prevent microbes from establishing an infection.

What is noteworthy about cathelicidin, however, is that it has both antimicrobialand pro-inflammatory properties. Too much CAMP is associated with autoimmune and inflammatory disease, and the featured study found that obese mice had more CAMP in their blood than those of normal weight.

According to Gallo:8

"…in humans it is becoming increasingly clear that the presence of AMPs can be a double-edged sword, particularly for CAMP. Too little CAMP and people experience frequent infections.

…The best example is atopic eczema (a type of recurring, itchy skin disorder). These patients can experience frequent Staph and viral infections. But too much CAMP is also bad. Evidence suggests excess CAMP can drive autoimmune and other inflammatory diseases like lupus, psoriasis and rosacea."

Obesity and Insulin Resistance May Increase Your Susceptibility to Infection by Altering AMP Production

If fat cells produce antimicrobial peptides, you might assume that someone with more fat cells would get even more protection against infection. Yet, the opposite actually holds true, both for obesity and the related condition insulin resistance. Both of these can alter AMP production. Gallo explained:

"Defective AMP production by mature adipocytes can occur due to obesity or insulin resistance, resulting in greater susceptibility to infection, but too much cathelicidin may provoke an unhealthy inflammatory response."

This may be one reason why obesity is associated with inflammation and is also an established risk factor for numerous infections, including skin infections.9There are still many unanswered questions about the role your fat cells play in immune response and disease.

Your body needs fat, but excess fat, such as in obesity, may alter your health in ways that have yet to be discovered. For now, the discovery that the fat beneath your skin may help ward off infection is a big one. As Gallo said:

"The key is that we now know this part of the immune response puzzle… these findings may help researchers understand disease associations with obesity and develop new strategies to optimize care."

Natural Ways to Boost Immune Function and Ward Off Infection

What happens to those pathogens that make it past the AMPs produced by your fat cells (or those that enter your body through your mouth, nose, ear, or eyes)? They can be easily defeated by a strong immune system, with the key word being strong.

You want to do everything you can to build and strengthen your immune system, which is your built-in defense against disease. There are quite a few ways to do this, including the natural steps outlined below:

• Optimize your vitamin D levels. I firmly believe that optimizing yourvitamin D levels is the single most important and least expensive action you can take to help strengthen immune function and protect against getting sick, especially during the flu season.
Vitamin D is an important player in overall healthy immune function, and it's also an effective antimicrobial agent in its own right, producing 200 to 300 different antimicrobial peptides in your body that kill bacteria, viruses and fungi. I strongly urge you to have your vitamin D level monitored to confirm your levels are optimized at 50-70 ng/ml year-round.
• Eat fermented foods: Fermented vegetables are an excellent way to supply beneficial bacteria back into your gut. As an added bonus, they can also be a great source of vitamin K2 if you ferment your own using the proper starter culture like Kinetic Culture. This is important because about 80 percent of your immune system resides in your gut, where healthy microflora is essential for a strong immune response. Also there's a connection between certain types of pathogenic bacteria in your gut and body fat that produces a heightened inflammatory response and drives the inflammatory process – all the more reason to nourish the beneficial varieties.
• Avoid sugar and grains: Excessive refined carbohydrates in the form of sugar and grains is very unbalancing for your gut flora. Sugar is "fertilizer" for pathogenic bacteria, yeast, and fungi that can set your immune system up for an easy assault by pathogens.
• Exercise: Exercise improves the circulation of immune cells in your blood. The job of these cells is to neutralize pathogens throughout your body. The better these cells circulate, the more efficient your immune system is at locating and defending against viruses and other pathogens that may otherwise opportunistically overrun your body.
• Manage your stress: When researchers from Carnegie Mellon University infected study participants with a common cold virus, those who had reported being under stress were twice as likely to get sick.10 Chronic stress also exerts a powerful negative influence on your epigenetic health, turning on and off the expression of genes that directly influence your likelihood of getting sick. Using techniques like energy psychology, you can correct the emotional short-circuiting that contributes to your chronic stress, which helps to optimize your genetic expression. My favorite technique for this is the Emotional Freedom Technique (EFT), but there are many others, such as yoga, journaling, and prayer.
• Use natural immune-boosters. Examples include oil of oregano and garlic, both of which offer effective protection against a broad spectrum of bacteria, viruses, and protozoa in your body. And unlike pharmaceutical antibiotics, they do not appear to lead to resistance and the development of "super germs."