Sunday, April 18, 2010

Got allergies? Get worms?

I heard about something this week that literally grossed me out. That is pretty difficult to do. I routinely gross other people out – occupational hazard. I talk about unsavory biological subjects at the dinner table (and just recently caused an innocent 9-year-old to lose her appetite). So, if I hear something that is too much even for me, you know it has got to be truly gross. It also means the gross thing is probably about parasites, because that is just about the only thing that sends me right over the top.

NPR recently featured a story about a gentleman who had bad allergies and asthma, and intentionally infected himself with hookworms as a way to “cure” them. I have allergies and asthma, and I am absolutely unwilling to infest myself with hookworm, or any other parasitic worm. But, I was intrigued.

The basis for this man’s actions was the observation that allergies and asthma are pretty rare in undeveloped countries; countries where parasite infestations are rampant. And, this is quite true. But, are parasites the reason for the low incidence of allergies? There are lots of other factors that could be at work here. For example, the first thing that springs to my mind is that we are simply too clean here in the US. Many studies have pointed out that we have sterilized our environment for our children to the point that they don’t build up immunity to the world around them as well as they used to. We are too clean. And, when they encounter the routine “stuff” floating around out there in the world, it affects them more strongly than it might otherwise. Simply put, our kids need to be allowed to get dirty.

But, it turns out there is some merit to this allergy-parasite trade-off. Parasites infect their hosts, but don’t want to kill them. If the parasite kills its host, then it too will die. A good parasite just knocks down the host’s immune system to the point that the host doesn’t attack it. And, so the theory goes, with your immune system slightly impaired, you are also less likely to develop allergic responses.

Only a handful of clinical trials have been conducted because it is difficult to work with human subjects and to intentionally infect them with parasites. The FDA won’t allow it in fact. But, a few researchers in Europe have managed to try a few studies with something close to rigorous experimental conditions. The results, so far, are mixed. Work at the University of Nottingham suggests a reduced sensitivity to skin-prick tests in individuals infested. However, studies at the same institution found only slight, and not scientifically significant, improvements in airway response.

So, if you are an allergy sufferer right now, I would suggest that infesting yourself with hookworms is, perhaps, extreme, and gross. But, there are strong leanings towards the notion that perhaps we can learn what hookworms do to their hosts, and mimic that, as an effective treatment for allergy sufferers.

Friday, April 2, 2010

How to mend a broken heart

Nope, this isn’t advice for the forlorn. I am referring to an actual physically broken heart. And, this represents cool science at its finest.

Researchers have long been interested in animals that can repair themselves. Lizards and salamanders can drop their tails if they are caught by a predator, and then re-grow them. Fish can repair damaged fins. But, we humans cannot re-grow a limb if lost. Can we figure out how these other animals do this and put it to work?

Recent work at the Salk Institute in San Diego purposely maimed the hearts of zebrafish (cute little aquarium fish you can find at your local pet store), and found they could regenerate up to 20% of that organ. That is a lot of heart to re-grow.

The heart is probably the most important organ in your body. I say probably because your brain is right up there in terms of keeping things going from minute to minute. If your heart is damaged, and you are losing blood, you’ve got only a few minutes left. But, zebrafish can stop the bleed, and then slowly, over days, repair the damage eventually producing a heart that was as good as the former.

How are they doing this? Science has long speculated that this is the work of stem cells. Stem cells are those cells that are not ‘determined’, meaning the kind of cell they are to become has not been decided yet by the body. They do not know yet what their job in life will be, be it bone cell or skin cell. Therefore, theoretically, we can use stem cells to initiate repairs.

Stem cell research has gotten a lot of attention lately, much of it controversial. The problem is, philosophically, where stem cells come from. We have some stem cells as adults, such as in our bone barrow; they don’t divide as well, cannot turn into as many things, and do not initiate repair as well as embryonic stem cells. Back in the 70’s scientists were able to make embryonic stem cells divide, meaning they can make more of them. Embryonic stem cells are completely undetermined, as opposed to adult stem cells, and most of our understanding of organ development and tissue repair has come from this line of work. Though, we have made breakthroughs in the last couple of years with adult stem cells. There is terrific coverage of this research and the controversy at the NIH website.

But, the amazing thing about this heart research is that it is not stem cells initiating the repair. Adult heart cells are doing the work. The adult heart cells initiate a repair response, much like a stem cell, and then divide rapidly to do the work. Other researchers tried this study in mice, to see if mammals could do what the fish could. They found out that the mammalian adult heart cells went back into a sort of stem cell like state and began to initiate repairs, but the cells did not proliferate, they did not divide. So, there were not enough of them to do the job. The trick now is getting them to proliferate. And, that is probably going to take some more research on stem cells to figure out how and why they proliferate, when the adult cells cannot.

In the meantime, try to keep your heart intact for a little while longer. We don’t have the fix quite yet.