For a long time scientists have been puzzled by the fact that the immune system in the gut is capable of fighting toxic bacterial infection while staying, at the same time, tolerant to its resident “friendly” bacteria. But an article now published in the journal Cell Host & Microbe(1) is starting to open the door to this mystery by revealing how a recently discovered gene - pims – is activated by the gut immune response against friendly bacteria to rapidly suppress it, effectively creating tolerance to the gut microbiota.
In the same way pims is also shown to control the magnitude of immune responses against toxic bacteria by suppressing immuno-reactivity when a certain activation threshold is achieved, assuring, in this way, that the response stays restricted to the infection site and is proportional to the extent of the infection. These results suggest that the balance tolerance/immuno-reaction in the gut is achieved through self-regulatory cycles where suppression by negative regulators, such as pims, is triggered as soon as a specific threshold of immuno activation is reached.
The architecture of haematopoiesis – which is the process by which all blood cells originate – is essentially the same throughout the mammal world, report scientists in the Proceedings of the Royal Society.
This is an unexpected result considering the thousands of mammals’ species with a myriad of habitats and lifestyles, as so well demonstrated when comparing the 30 mm flying bumblebee bat and the 30 metre-long aquatic blue whale both mammals.
But the work now published shows that the variations in the blood system - necessary to adapt to the evolutionary changes found within the mammals’ world -can be explained quantitatively (for example by producing more cells or having the cells dividing faster), and are directly correlated to the animals’ body mass and do not require any fundamental alteration in the haematopoietic process.