Uloga mikrobiote i limfnog tkiva creva u otpornosti pacova soja Albino Oksford na indukciju eksperimentalnog autoimunskog encefalomijelitisa
Role of gut microbiota and gut-associated lymphoid tissue in resistance of Albino Oxford rats to experimental autoimmune encephalomyelitis induction
2018
Authors:
Stanisavljević, SuzanaContributors
Miljković, ĐorđeBožić Nedeljković, Biljana
Golić, Nataša
Document Type:
Doctoral thesis (Published version)
Metadata
Show full item recordAbstract:
Multiple sclerosis is a chronic inflammatory neurodegenerative demyelinating disease of the central nervous system (CNS). Etiology of multiple sclerosis is still unknown, but data are showing that gut microbiota plays an important role in the pathogenesis of this disease. Information about the significance of gut microbiota in CNS autoimmunity has been dominantly obtained in studies in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. The autoimmune response against CNS starts in lymph nodes draining the site of immunization in EAE. There, CD4+ T cells are being activated and differentiated into Th1 (helper T cells) and Th17 cells that produce IFN-γ and IL-17, respectively. When Th cells arrive in the CNS, they are reactivated by local antigen-presenting cells. After the reactivation, these encephalitogenic T cells initiate and propagate CNS inflammation.
Albino Oxford (AO) rats are highly resistant to EAE induction. On the other hand, Dark Agouti (DA) rats develop EAE even after the mild immunization. In our earlier studies it was shown that AO rats had less activated Th1 and Th17 cells in the relevant lymph nodes in response to encephalitogenic immunization, unlike DA rats. Also, it was shown that relatively small number of encephalitogenic cells infiltrated CNS in AO rats. Up until now, the studies of role of GALT and gut microbiota in resistance of AO rats in EAE induction have not been conducted.
It has been increasingly appreciated that gut microbiota plays an important role in the regulation of the immune response through interaction with the cells of gut-associated lymphoid tissue (GALT). In EAE studies specific gut microorganisms have been proposed to promote the disease, while others have been shown to have therapeutic effects by modulating ratio and activity of encefalitogenic Th1 and Th17 cells and regulatory T cells (Treg). Encefalitogenic cells can also migrate to GALT, including mesenteric lymph nodes and Peyer’s patches, where they can be re-differentiated into
Treg. It is considered that intrinsic bacteria and their products play an important role in this re-differentiation. That is why it has become important to determine which bacteria and in what ways are implicated in multiple sclerosis pathogenesis, to prevent and treat the disease by modulating gut microbiota. Recent comparative studies of gut microbiota content of multiple sclerosis patients and healthy individuals have shown increased presence of some groups of bacteria in patients, including Clostridia clusters XIV and IV, Bacteroides fragilis, and Pseudomonas, Mycoplana, Haemophilus, Dorea, Blautia. However, the results of previous studies cannot clarify what are the mechanisms of contribution of gut microbiota to pathogenesis of multiple sclerosis.
Gut microbiota and GALT are considered to be important players in initiation, propagation, but also in prevention of CNS autoimmunity. Gut microbiota content differs among multiple sclerosis patients and healthy subjects. In accordance to that, EAE-resistant rat strain and EAE-prone rat strain have different gut microbiota content in our experiments. Specifically, Turicibacter sp. and members of Lachnospiraceae family are identified as possible promoters of EAE resistance or EAE recovery. Besides, it was demonstrated that mesenteric lymph nodes and Peyer’s patches differ between AO and DA rats. DA rats have higher proportion of CD4+ cells and more Tregs. Further, GALT cells of EAE-resistant rat strain produced less IFN-γ and IL-17 in comparison to EAE-prone rat strain. Production of IL-10, major immunoregulatory cytokine, was also different among these rat strains.
Antibiotic treatment disturbed EAE resistance in AO rats. It was observed in the form of mild clinical symptoms, higher number of spinal cord infiltrates and a higher concentration of IL-17 in the CNS. Antibiotic effects were seen in lymph nodes draining the site of immunization; they had higher cellularity, a higher proportion of CD4+ cells, and higher production of proinflammatory cytokines. Treg analysis showed that there was a difference in Peyer’s patches of unimmunized rats. After the immunization, less Treg was observed in draining lymph nodes, mesenteric lymph nodes and Peyer’s patches in antibiotic treated rats. Gut microbiota content of AO rats was significantly changed after four weeks of antibiotic treatment.
Gut microbiota transfer from AO rats into DA rats resulted in milder EAE symptoms in DA rats and lower concentration of IL-17 in CNS. Increased proportion of
Treg was observed in draining lymph nodes in the treated animals. Gut microbiota transfer led to more significant changes in gut microbiota diversity of treated rats, especially in lactic acid bacteria.
Results of this doctoral thesis clearly demonstrate important role of gut microbiota in the pathogenesis of the CNS autoimmunity. They also imply that modulation of gut microbiota could be used as a novel therapeutic approach in multiple sclerosis.
Keywords:
Experimental autoimmune encephalomyelitis; Albino Oxford rat; Gut microbiota; Gut-associated lymphoid tissueSource:
University of Belgrade, Faculty of Biology, 2018, 1-134Funding / projects:
- Cellular and molecular mechanisms of recovery of rats from experimental autoimmune encephalomyelitis (RS-MESTD-Basic Research (BR or ON)-173035)
- Molecular mechanisms of physiological and pharmacological control of inflammation and cancer (RS-MESTD-Basic Research (BR or ON)-173013)
URI
http://uvidok.rcub.bg.ac.rs/handle/123456789/2612https://radar.ibiss.bg.ac.rs/handle/123456789/3105