Fat Isn’t All Bad: Skin Adipocytes Help Protect Against Infections

When it comes to skin infections, a healthy and robust immune response may depend greatly upon what lies beneath. In a new paper published in the January 2, 2015 issue of Science, researchers at the University of California, San Diego School of Medicine report the surprising discovery that fat cells below the skin help protect us from bacteria.

Richard Gallo, MD, PhD, professor and chief of dermatology at UC San Diego School of Medicine, and colleagues have uncovered a previously unknown role for dermal fat cells, known as adipocytes: They produce antimicrobial peptides that help fend off invading bacteria and other pathogens. … Read the full story from the UC San Diego Newsroom


Dr. Richard Gallo

Dr. Richard Gallo

Richard Gallo, MD, PhD, is professor of medicine and pediatrics and chief of the Division of Dermatology.

Read Science article abstract on PubMed

Visit Dr. Gallo’s laboratory website

Hormone Plays Surprise Role in Fighting Skin Infections

Boosts immune response when vitamin D levels are low

Antimicrobial peptides (AMPs) are molecules produced in the skin to fend off infection-causing microbes. Vitamin D has been credited with a role in their production and in the body’s overall immune response, but scientists at the University of California, San Diego School of Medicine say a hormone previously associated only with maintaining calcium homeostasis and bone health is also critical, boosting AMP expression when dietary vitamin D levels are inadequate. … Read the full story from the UCSD Newsroom


Dr. Richard GalloThe report comes from Dr. Richard Gallo (pictured at left) and colleagues at UC San Diego, the Veterans Affairs San Diego Healthcare System, and UC San Francisco.

Richard L. Gallo, MD, PhD, is professor of medicine and chief of the UCSD Division of Dermatology and the Dermatology section of the Veterans Affairs San Diego Healthcare System.

The Department of Medicine coauthors of the study are first author Beda Muehleisen, Carlos Aguilera, and George L. Sen, Division of Dermatology, UC San Diego; Douglas W. Burton, Veterans Administration San Diego Healthcare System; and Leonard J. Deftos, MD, JD, LLM, Veterans Administration San Diego Healthcare System and Division of Endocrinology and Metabolism, Department of Medicine, UC San Diego.

More information:

  • Read the article in Science Translational Medicine.
    Citation: B. Muehleisen, D. D. Bikle, C. Aguilera, D. W. Burton, G. L. Sen, L. J. Deftos, R. L. Gallo, PTH/PTHrP and Vitamin D Control Antimicrobial Peptide Expression and Susceptibility to Bacterial Skin Infection. Sci. Transl. Med. 4, 135ra66 (2012). DOI:10.1126/scitranslmed.3003759
  • Visit Dr. Gallo’s Laboratory Website

In the Frontiers of Dermatology Research with Dr. Richard Gallo and Coworkers

Dr. Richard GalloAs they trace the causes of some common but poorly understood skin disorders, Dr. Richard Gallo and his colleagues at UCSD are finding themselves at the edge of the known world in dermatology and immune defense.

Richard Gallo, MD, PhD, Professor and Chief of Dermatology at UCSD and Chief of the Dermatology Section at the Veterans Administration San Diego Healthcare System (VASDHS), says he feels fortunate to be working in this exciting area of investigation.

He is also particularly glad to be here at UCSD in San Diego.

“It’s a vibrant research environment,” he says, naming the many major institutions that collaborate here, among them the Salk Institute and The Scripps Research Institute as well as UCSD.

“We have done what we’ve done here,” he says, “because we are here.”


UCSD and its neighboring institutions –
“A vibrant research environment”


Rob Dorschner, manager of Dr. Gallo's laboratory
At left: Rob Dorschner, manager
of Dr. Gallo’s dermatology
research laboratories.

Last year, Dr. Gallo and his coworkers reported a major finding in acne rosacea, a chronic skin inflammation that affects approximately 14 million adults in the U.S.

Rosacea can cause skin redness, visible blood vessels, facial burning or swelling, and bumps or pustules on the skin.

The cause of rosacea was a mystery until Dr. Gallo and colleagues found that the skin’s immune defenses are abnormal in three different ways in people who have it.

Unexpectedly, the abnormalities are in the innate immune system, an aspect of the body’s defenses that was not considered important in humans until recently.


Some of the latest findings
may bring new hope to millions
who suffer from acne rosacea


The report from Dr. Gallo and his international team of researchers was published in Nature Medicine last fall.

The study was supported by funding from National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health, the National Rosacea Society, a Veterans Administration Merit Award to Dr. Gallo, and the Association for Preventive Medicine of Japan.

The findings from Dr. Gallo’s lab may open the way for researchers to develop new acne rosacea treatments that address the real cause of the problem.

As a result, there is new hope for individuals who are affected by this uncomfortable and unpredictable disorder.

Dr. Amanda Buchau
At left: Dr. Amanda Büchau,
researcher in Dr. Gallo’s
laboratory.

The innate immune system is a new area of inquiry for researchers who are looking for the causes of skin disorders.

The very first defense mechanism of an organism, the innate immune system is genetically determined. “It’s evolutionarily ancient,” Dr. Gallo says. “All organisms have it. Like plants and sea sponges, humans have it.”

The innate immune system can recognize a dangerous molecule without having been exposed to it before.


Until recently, the innate immune response
was ignored in humans.


The other major component of our immune defenses is the adaptive immune system, which must learn through exposure — either by actual infection or by immunization.Why was the innate immune system ignored before?

“Because it’s hard to see,” Dr. Gallo says. When early investigators conducted their first studies of immune defenses in the skin, they focused literally on what was visible.

The pus in a skin wound, for example, is a clearly visible reaction to infection. It is a product of the adaptive immune system, and it drew the attention of researchers to that aspect of our immune defenses.

Meanwhile, the innate immune system was considered less important in humans than it was in simpler organisms.


“It has become clear that
the innate immune system
in humans
is really essential.”


As a result, many of the molecules involved in the innate immune system were not discovered until recent years.

“Now,” says Dr. Gallo, “it has become clear that the innate immune system in humans is really essential.”

Discovering more about innate immunity continues to be one of the aims of Dr. Gallo’s studies. His rosacea research is part of a much larger effort to shed light on the way the innate immune system works to protect the skin.

He and his researchers are seeking to identify all the factors that influence the way our defenses work. These include our genetics, our biochemistry, our environment, and the “bugs” themselves.

Dr. Gallo’s studies have yielded important and sometimes surprising results. One was that the amount of Vitamin D available to us has an important effect on the health of our skin.

He found that Vitamin D is an essential hormone in the control of the skin’s innate defenses.

Currently, Dr. Gallo is focusing his research on antimicrobial peptides, “the effectors of innate immunity.” The innate immune system deploys antimicrobial peptides to defend the skin from infection when it recognizes a harmful invader.

It was in antimicrobial peptides that Dr. Gallo and his coworkers found the abnormalities they reported in the immune defenses of acne rosacea sufferers last year.

Dr. Gallo’s goal is to discover new antimicrobial peptides and to learn how they are associated with human diseases, how they work, and how they are controlled.


Dr. Gallo’s work focuses on
developing better care for skin diseases
such as atopic dermatitis and acne rosacea


Dr. Gallo and his team pursue translational research, a high priority in the Department of Medicine at UCSD. The aim of translational research is to focus laboratory researchers on projects that will lead directly to better diagnosis and treatment of disease.

Dr. Gallo’s laboratory studies are concentrated on developing better care for skin diseases such as atopic dermatitis and acne rosacea.

Atopic dermatitis is an inflammatory skin disease in which the skin is unusually susceptible to infection. Affected individuals are not able to make antimicrobial peptides normally, and Dr. Gallo is investigating how to correct this defect.

In chronic inflammatory disorders such as acne rosacea, Dr. Gallo’s work is aimed at pinpointing the root causes. In rosacea, he and his coworkers found abnormally high amounts of certain antimicrobial peptides.

Such abnormalities are inherited. Heredity determines the biochemistry of an individual’s immune response, and it is in that biochemistry – a many-tiered system of molecules and interactions – that the targets for future treatments can be found.


The human skin –
important, accessible,
but mysterious


Dr. Gallo’s early training was in biophysics and pediatrics. He earned his M.D. degree and a Ph.D. in radiation biology and biophysics from the University of Rochester.

He became interested in the study of the skin because of its importance in human health, its accessibility, and its mystery — there was relatively little understanding of the skin’s defenses. He saw dermatology research as a wide-open field.

He currently holds a joint appointment in Medicine and Pediatrics. Although he is involved in Pediatrics in a relatively minor way at this point, he is interested in the development of the skin, a process that does not stop at the arbitrary age of chronological maturity.

He is also interested in how the skin’s immune defenses change as an individual goes through life.


“The San Diego research community
is clearly one of the leaders
in research in innate immunity.”


Dr. Gallo finds it invaluable to be part of the larger investigative environment in which UCSD is situated.

“The San Diego research community is clearly one of the leaders in research in innate immunity,” he says.

In addition to his own field of dermatology, he says, exciting investigations are going on in many body systems including the gastrointestinal system and the lung.

“It’s a great, open, communicative group of researchers that’s dynamic,” he says. “It’s fun to work here and be part of it.”


UCSD Dermatology residents –
“the best and the brightest.”


Dr. Gallo is proud of the UCSD Dermatology Residency Training Program.“It is one of the most competitive programs around,” he says. “We are dedicated to outstanding clinical teaching as well as training the future academic leaders in dermatology.”

Over half of the current residents have both MD and PhD degrees. For its three residency slots available each year, UCSD Dermatology receives 300-400 applications.

“We get the best and the brightest,” Dr. Gallo says.

More Information:

Photo of Dr. Gallo, top left of this article, by Joyce Roberts.