Legatura intre creier si sistemul imunitar

Descoperire 2015:

Remarcabila legatura intre creier si sistemul imunitar

 

Intr-o descoperire remarcabila care da peste cap decenii de studii bazate pe cunostintele din carti, cercetatorii de la University of Virginia School of Medicine au demonstrat conectarea creierului la sistemul imunitar prin intermediul unor vase a caror existenta nu era cunoscuta pana in prezent.

 

Faptul ca astfel de vase au putut scapa detectiei cand sistemul limfatic a fost atat de amanuntit cartografiat la nivelul intregului organism este surprinzator, dar adevarata importanta a acestei descoperiri consta in efectele pe care le-ar putea avea asupra studiului si tratamentului bolilor neurologice, de la autism la boala Alzheimer si scleroza multipla.

Legatura intre creier si sistemul imunitar

Photo: Harta sistemului limfatic: varianta veche (stanga) si cea actualizata pentru a corespunde descoperirii de la UVA.

Sursa: University of Virginia Health System

 

„In loc sa ne intrebam ‚Cum studiem raspunsul imunitar al creierului?’ ‚De ce pacientii cu scleroza multipla prezinta atacurile imunitare?’, acum putem sa abordam aceste subiecte din punct de vedere fiziologic.

Deoarece creierul este asemenea oricarui alt tesut conectat la sistemul imunitar periferic prin intermediul vaselor limfatice meningeale”, afirma prof. dr. Jonathan Kipnis, profesor la Departamentul de neurostiinte al UVA si director al Center for Brain Immunology and Glia (BIG) din cadrul UVA.

„Aceasta descoperire schimba in intregime modul in care percepem interactiunea neuro-imunitara. Am perceput-o intotdeauna ca pe ceva ezoteric care nu poate fi studiat. Dar acum putem adresa intrebari fiziologice.”

„Credem ca pentru fiecare boala neurologica care prezinta o componentă imunologica, aceste vase ar putea juca un rol crucial”, afirmă Kipnis. „Este greu de crezut ca aceste vase nu ar fi implicate intr-o boala neurologica cu o componenta imunitara.”

 

O noua descoperire in corpul uman
Prof. dr. Kevin Lee, directorul Departamentului de neuroştiinţe de la UVA, a descris reactia sa la descoperirea laboratorului lui Kipnis:         „Prima data cand acesti tipi mi-au prezentat rezultatele initiale, nu am spus decat o fraza: „Trebuie sa schimbe cartile.”  Nu a existat niciodata un sistem limfatic pentru sistemul nervos central, si a fost foarte clar de la acea prima singura observatie – au realizat numeroase studii de atunci pentru a sustine descoperirea – ca va schimba fundamental modul in care oamenii vor analiza relatia sistemului nervos central cu sistemul imunitar.”

 

Chiar și Kipnis a fost sceptic la inceput. „Nu imi venea sa cred ca exista structuri la nivelul organismului de a caror existenta sa nu fim constienti. Am crezut ca organismul a fost cartografiat complet”, subliniaza acesta. „Am crezut ca aceste descoperiri au luat sfarsit undeva pe la mijlocul secolului trecut. Dar se pare ca nu.”

 

„Foarte bine ascuns”
Descoperirea a fost posibila multumita cercetatorilor lui Antoine Louveau, care-si desfasoara studiile postdoctorale in laboratorul lui Kipnis. Vasele au fost descoperite dupa ce Louveau a dezvoltat o metoda de a monta meningele unui soarece – membranele care inconjoara creierul – pe o singura lama, pentru a putea fi analizate ca un intreg. „A fost destul de usor, de fapt”, afirma acesta. „A existat un truc: am fixat meningele pe calota, astfel incat tesutul este in siguranta in conditiile sale fiziologice, iar apoi l-am disecat. Daca am fi procedat invers, nu ar fi functionat.”
Dupa ce a observat un model asemanator vaselor limfatice in distributia de celule imunitare de la nivelul lamelor sale, a facut un test pentru a detecta vase limfatice si acestea erau acolo. Imposibilul există. Louveau rememoreaza momentul: „L-am chemat pe Jony [Kipnis] la microscop si i-am spus: ‚Cred ca avem ceva.’ ”
In ceea ce priveste modul in care vasele limfatice au reusit sa scape detectiei precedente in tot acest timp, Kipnis le descrie ca fiind „foarte bine ascunse” si subliniaza ca acestea urmaresc un vas de sange major la nivelul sinusurilor, o zona dificil de descris. „Sunt atat de aproape de vasele de sange, incat le ratezi cu usurinta”, spune Kipnis. „Daca nu stii ceea ce cauti, este usor de trecut peste.”
„Prezentarea in vivo a acestor vase a fost cruciala pentru a le demonstra functia si nu ar fi fost posibila fara colaborarea lui Tajie Harris”, noteaza Kipnis.  Harris este profesor asistent in neurostiinte si membru al centrului BIG.  Kipnis a salutat, de asemenea, abilitatile chirurgicale „fenomenale” ale lui Igor Smirnov, cercetator asociat in laboratorul lui Kipnis a carui activitate a fost cruciala pentru succesul prezentarii in vivo din cadrul studiului.

 

Alzheimer, autism, scleroza multipla si dincolo de acestea

 

Prezenta neasteptata a vaselor limfatice ridica un numar imens de intrebari care necesita raspunsuri atat in legatura cu functionarea creierului, cat si a bolilor care-l afecteaza.

De exemplu, sa luăm boala Alzheimer. „În Alzheimer, exista acumulari de placi de proteine imense la nivelul creierului”. Credem ca se acumuleaza la nivelul creierului, intrucat nu sunt suficient de bine eliminate de catre aceste vase.”

Acesta a remarcat ca vasele au un aspect diferit odata cu varsta, astfel incat rolul pe care-l joaca in imbatranire este o alta pista de investigat.

Si este o serie enorma de alte boli neurologice, de la autism la scleroza multipla care trebuie reconsiderata in lumina prezentei unor structuri despre care stiinTa nu era la curent ca ar exista.

Descoperirile au fost publicate online

de catre prestigioasa revista Nature.

 

Traducere de Vijiala Sergiu dupa link-brain-immune,

cu acordul editorului.

 

Sursa: http://www.scientia.ro/blog-sergiu-vijiala/6626-creier-sistem-imunitar-legatura.html

 

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Missing link found between brain, immune system

 

        Maps of the lymphatic system:

old (left) and updated to reflect UVA’s discovery.

Credit: University of Virginia Health System

 

In a stunning discovery that overturns decades of textbook teaching, researchers at the University of Virginia School of Medicine have determined that the brain is directly connected to the immune system by vessels previously thought not to exist.

That such vessels could have escaped detection when the lymphatic system has been so thoroughly mapped throughout the body is surprising on its own, but the true significance of the discovery lies in the effects it could have on the study and treatment of neurological diseases ranging from autism to Alzheimer’s disease to multiple sclerosis.

 

“Instead of asking, ‘How do we study the immune response of the brain?’ ‘Why do multiple sclerosis patients have the immune attacks?’ now we can approach this mechanistically.  Because the brain is like every other tissue connected to the peripheral immune system through meningeal lymphatic vessels,” said Jonathan Kipnis, PhD, professor in the UVA Department of Neuroscience and director of UVA’s Center for Brain Immunology and Glia (BIG).

“It changes entirely the way we perceive the neuro-immune interaction. We always perceived it before as something esoteric that can’t be studied. But now we can ask mechanistic questions.”

 

“We believe that for every neurological disease that has an immune component to it, these vessels may play a major role,” Kipnis said. “Hard to imagine that these vessels would not be involved in a [neurological] disease with an immune component.”

 

New Discovery in Human Body

 

Kevin Lee, PhD, chairman of the UVA Department of Neuroscience, described his reaction to the discovery by Kipnis’ lab:   “The first time these guys showed me the basic result, I just said one sentence: ‘They’ll have to change the textbooks.’ There has never been a lymphatic system for the central nervous system, and it was very clear from that first singular observation – and they’ve done many studies since then to bolster the finding – that it will fundamentally change the way people look at the central nervous system’s relationship with the immune system.”

 

Even Kipnis was skeptical initially. “I really did not believe there are structures in the body that we are not aware of. I thought the body was mapped,” he said. “I thought that these discoveries ended somewhere around the middle of the last century. But apparently they have not.”

 

‘Very Well Hidden’

 

The discovery was made possible by the work of Antoine Louveau, PhD, a postdoctoral fellow in Kipnis’ lab. The vessels were detected after Louveau developed a method to mount a mouse’s meninges – the membranes covering the brain – on a single slide so that they could be examined as a whole. “It was fairly easy, actually,” he said. “There was one trick: We fixed the meninges within the skullcap, so that the tissue is secured in its physiological condition, and then we dissected it. If we had done it the other way around, it wouldn’t have worked.”

 

After noticing vessel-like patterns in the distribution of immune cells on his slides, he tested for lymphatic vessels and there they were. The impossible existed. The soft-spoken Louveau recalled the moment: “I called Jony [Kipnis] to the microscope and I said, ‘I think we have something.’

 

As to how the brain’s lymphatic vessels managed to escape notice all this time, Kipnis described them as “very well hidden” and noted that they follow a major blood vessel down into the sinuses, an area difficult to image. “It’s so close to the blood vessel, you just miss it,” he said. “If you don’t know what you’re after, you just miss it.”

 

“Live imaging of these vessels was crucial to demonstrate their function, and it would not be possible without collaboration with Tajie Harris,” Kipnis noted. Harris, a PhD, is an assistant professor of neuroscience and a member of the BIG center. Kipnis also saluted the “phenomenal” surgical skills of Igor Smirnov, a research associate in the Kipnis lab whose work was critical to the imaging success of the study.

 

Alzheimer’s, Autism, MS and Beyond

 

The unexpected presence of the lymphatic vessels raises a tremendous number of questions that now need answers, both about the workings of the brain and the diseases that plague it.

For example, take Alzheimer’s disease. “In Alzheimer’s, there are accumulations of big protein chunks in the brain,” Kipnis said. “We think they may be accumulating in the brain because they’re not being efficiently removed by these vessels.”

He noted that the vessels look different with age, so the role they play in aging is another avenue to explore.

And there’s an enormous array of other neurological diseases, from autism to multiple sclerosis, that must be reconsidered in light of the presence of something science insisted did not exist.

 

The findings have been published online by the prestigious journal Nature and will appear in a forthcoming print edition.

 

Source:

http://medicalxpress.com/news/2015-06-link-brain-immune.html