Hormone works in tandem with vitamin D to fight skin infections

A certain hormone works in tandem with vitamin D to control how skin cells produce a natural microbe-fighting agent, and can compensate for a lack of vitamin D, scientists have found.

The new results help explain something that has confused researchers for a long time: although it is known that vitamin D plays a role in the immune defense, there are very few clinical trials that show that taking supplemental vitamin D helps prevent infection.

The work was led by Richard Gallo, a professor of medicine and pediatrics and chief of the Division of Dermatology at the University of California, San Diego. It was published this week in the journal Science Translational Medicine.

The skin makes natural antimicrobial compounds (protein fragments called peptides) to kill unwanted bacteria, fungi, and viruses. Eczema patients produce these compounds at lower levels than normal; psoriasis patients, at higher levels. Vitamin D initiates production of cathelicidin, a broad-spectrum antimicrobial.

Gallo and colleagues showed that human skin cells produce parathyroid hormone (PTH) when treated with a bacterial compound known to trigger the immune system. The same cells, stimulated with vitamin D, manufactured copies of the receptor for PTH. And the skin cells produce far more cathelicidin when they are treated with parathyroid hormone and vitamin D than with either compound alone.

The results suggest a model in which, in humans, vitamin D can stimulate cathelicidin production by itself—but PTH is doing so by a parallel pathway, which vitamin D can amplify.

The scientists also showed that PTH helps reduce the severity and extent of Streptococcus skin infections in mice—but it does so much more strongly in normal mice, compared to mice genetically engineered to be unable to convert vitamin D to its active form. (Apparently it is very difficult to make a mouse deficient in vitamin D.)

What this means for eczema patients is not clear yet. The research gets us further toward understanding how vitamin D and other factors participate in the skin’s immune response. If I were a doctor, it would make me hesitant to recommend that patients with normal vitamin D levels should take supplements.

It's haircut time!

Fingernail trimming tonight for Voov before her bath. The usual circus of book-reading to distract her, and Shmoop crowding in, blocking out the light so Hidden B can't see well enough to trim off the sharp little edges with which Voov mangles herself. Her skin hasn't been too bad of late, but she's got a patch of eczema on her torso that she was scratching away at with whatever hand wasn't being trimmed.

I read somewhere that infants with eczema exposed to emollients containing peanut protein were at higher risk of becoming allergic to peanuts. The Derma-Smoothe oil we use on Voov contains peanut oil, according to the ingredients. But apparently the proteins have been denatured-- by heat treatment?--or broken down somehow so that they are not allergenic. That's what Hidden B told me when I brought the matter up. The dermatologist said that she'd even applied Derma-Smoothe to a kid with a peanut allergy and seen no reaction. Now that takes some cojones. Why is the manufacturer using peanut oil? It must have some remarkable lubricating properties.

My big achievement of the day was getting a haircut. I'm at the age when my head is only really growing hair around the sides and the back, but you still have to get it cut every once in a while if you don't want to look like this guy.

Inconceivable!

Getting a haircut for me is a matter of timing. I have to do it on days when eczema isn't running rampant on my scalp. (It favors the back of my head.) Sometimes put off getting a haircut for weeks because 1) I've never been keen on letting anyone look closely at my scabs and 2) I've always thought a barbershop would be a fine place to pick up an infection. Sometimes you see barbers take those scissors from the jars of blue sterilizing fluid, and sometimes they just buzz your head with clippers that most likely were just on some other dude's head a few minutes ago. I get my hair cut in downtown San Francisco, which about thirty years ago was where AIDS first broke into the news. Always makes me nervous.

This morning I realized my head was an eczema-free zone. And I was getting shaggy in back. So off to SuperCuts at lunch.

I used to cut my own hair-- well, buzz it really-- but in my current job it isn't an option. Wouldn't look good if I missed a spot, as I've been known to do. Last time I went to a barbershop near home I got some gloomy lady who, besides boring the hell out of me talking about firearms, told me that the guy whose ass was responsible for warming the chair I was sitting in had had a fungal infection all over his head. It was a total Seinfeld situation. She told me that sterilization was priority #1 for barbers. I wanted to leap out of the chair and run screaming from the shop, but didn't want to make her feel bad. I got the haircut. It was no better or cheaper than the one in San Francisco.

So, the moral of the story? Maybe I ought to flatter Hidden B that she's got mad styling skillz.