With modern plumbing and hygiene, the number of nasty microbes we humans are exposed to has plummeted, while the rate of autoimmune diseases and allergies has shot up. Are those related? Proponents of the hygiene hypothesis think so: our immune system is supposed to develop by encountering microbes, so being too clean throws it out of whack as the immune system overreacts to minor insults.
A new study found that mice raised germ-free had especially high numbers of invariant natural killer T cells (iNKT) in their colons and lungs—the mouse versions of inflammatory bowel disease and asthma, respectively. Most evidence supporting the hygiene hypothesis has just been in observed correlations, so this research that identifies a plausible molecular mechanism is good evidence for how over-cleanliness might cause immune dysfunction.
A woman with kidney disease has died after receiving an experimental stem cell treatment at a private clinic in Thailand, and a postmortem examination of her kidneys revealed that the treatment was almost certainly responsible for her death. Last week we reported that Costa Rica’s health ministry had closed a stem cell clinic that catered to foreigners, which sparked lively debates around the Internet about whether patients should be able to willingly take on risks associated with experimental treatments. This new case offers a sobering reminder of what can happen when patients travel abroad looking for a miracle cure.
The woman suffered from lupus nephritis, a disease in which the immune system attacks the kidneys. When medications no longer controlled her disease, she went to a still-unnamed clinic in Bangkok where doctors said they could treat her disease using stem cells drawn from her own bone marrow. There was some medical rationale for this:
Bona-fide trials in European clinics about six years ago showed that some people with similar kidney disease benefited if stem cells from their own bone marrow were injected into their blood. The body’s immune system was first deliberately destroyed with powerful immunosuppressive drugs, then the reinjected stem cells helped to stop the attacks on the kidney by rebuilding and rebalancing the immune system. [New Scientist]
However, the Thai clinic didn’t inject the stem cells into the patient’s blood stream, instead they injected them directly into her kidneys. That means the stem cells did nothing to stop the immune system’s attack on the organs–and they instead produced never-before-seen side effects.