The microbiota regulates murine inflammatory responses to toxin-induced CNS demyelination but has minimal impact on remyelination.

The microbiota is now recognized as a key influence on the host immune response in the central nervous system (CNS). As such, there has been some progress toward therapies that modulate the microbiota with the aim of limiting immune-mediated demyelination, as occurs in multiple sclerosis. However, remyelination-the regeneration of myelin sheaths-also depends upon an immune response, and the effects that such interventions might have on remyelination have not yet been explored. Here, we show that the inflammatory response during CNS remyelination in mice is modulated by antibiotic or probiotic treatment, as well as in germ-free mice. We also explore the effect of these changes on oligodendrocyte progenitor cell differentiation, which is inhibited by antibiotics but unaffected by our other interventions. These results reveal that high combined doses of oral antibiotics impair oligodendrocyte progenitor cell responses during remyelination and further our understanding of how mammalian regeneration relates to the microbiota.This work was supported by grants from UK Multiple Sclerosis Society, The British Trust for the Myelin Project, MedImmune, The Adelson Medical Research Foundation, Wellcome Trust, BBSRC, the Leverhulme Trust and a core support grant from the Wellcome Trust and MRC to the Wellcome Trust - Medical Research Council Cambridge Stem Cell Institute. CEM was supported by grants from the Jean Shanks Foundation and the James Baird Fund, AGF was supported by an ECTRIMS fellowship and OBZ received a BIRAX fellowship

Ageing impairs the regenerative capacity of regulatory T cells in mouse central nervous system remyelination

Myelin regeneration (remyelination) is essential to prevent neurodegeneration in demyelinating diseases such as Multiple Sclerosis, however, its efficiency declines with age. Regulatory T cells (Treg) recently emerged as critical players in tissue regeneration, including remyelination. However, the effect of ageing on Treg-mediated regenerative processes is poorly understood. Here, we show that expansion of aged Treg does not rescue age-associated remyelination impairment due to an intrinsically diminished capacity of aged Treg to promote oligodendrocyte differentiation and myelination in male and female mice. This decline in regenerative Treg functions can be rescued by a young environment. We identified Melanoma Cell Adhesion Molecule 1 (MCAM1) and Integrin alpha 2 (ITGA2) as candidates of Treg-mediated oligodendrocyte differentiation that decrease with age. Our findings demonstrate that ageing limits the neuroregenerative capacity of Treg, likely limiting their remyelinating therapeutic potential in aged patients, and describe two mechanisms implicated in Treg-driven remyelination that may be targetable to overcome this limitation

Regulatory T cells promote myelin regeneration in the central nervous system

Regeneration of CNS myelin involves differentiation of oligodendrocytes from oligodendrocyte progenitor cells. In multiple sclerosis, remyelination can fail despite abundant oligodendrocyte progenitor cells, suggesting impairment of oligodendrocyte differentiation. T cells infiltrate the CNS in multiple sclerosis, yet little is known about T cell functions in remyelination. We report that regulatory T cells (T$_{reg}$) promote oligodendrocyte differentiation and (re)myelination. T$_{reg}$-deficient mice exhibited substantially impaired remyelination and oligodendrocyte differentiation, which was rescued by adoptive transfer of T$_{reg}$. In brain slice cultures, T$_{reg}$ accelerated developmental myelination and remyelination, even in the absence of overt inflammation. T$_{reg}$ directly promoted oligodendrocyte progenitor cell differentiation and myelination in vitro. We identified CCN3 as a T$_{reg}$-derived mediator of oligodendrocyte differentiation and myelination in vitro. These findings reveal a new regenerative function of T$_{reg}$ in the CNS, distinct from immunomodulation. Although the cells were originally named 'T$_{reg}$' to reflect immunoregulatory roles, this also captures emerging, regenerative T$_{reg}$ functions.This work was supported by the Biotechnology and Biological Sciences Research Council (BB/J01026X/1 and BB/N003721/1, to D.C.F.), The Leverhulme Trust (ECF-2014-390, to Y.D.), QUB (QUB - Lucy McGuigan Bequest, to D.C.F.), The UK Multiple Sclerosis Society (941 and 50, to R.J.M.F. and C.Z.), MRC UK Regenerative Medicine platform (MR/KO26666/1, to A.C.W.), University of Edinburgh Wellcome Trust Multi User Equipment Grant (WT104915MA, to A.C.W.), by a core support grant from the Wellcome Trust and MRC to the Wellcome Trust - Medical Research Council Cambridge Stem Cell Institute (097922/Z/11/Z to R.J.M.F.), studentship support from Dept. for the Economy (Northern Ireland) and British Pathological Society, US National Multiple Sclerosis Society (RG5203A4, to J.R.C.), NIH/NINDS (NS095889, to J.R.C.), NIH/NIGMS IRACDA Postdoctoral Fellowship (K12GM081266, to S.R.M.) and Wellcome Trust (110138/Z/15/Z, to D.C.F.)

Loss of Synaptic Connectivity, Particularly in Second Order Neurons Is a Key Feature of Diabetic Retinal Neuropathy in the Ins2^Akita Mouse

Retinal neurodegeneration is a key component of diabetic retinopathy (DR), although the detailed neuronal damage remains ill-defined. Recent evidence suggests that in addition to amacrine and ganglion cell, diabetes may also impact on other retinal neurons. In this study, we examined retinal degenerative changes in Ins2Akita diabetic mice. In scotopic electroretinograms (ERG), b-wave and oscillatory potentials were severely impaired in 9-month old Ins2Akita mice. Despite no obvious pathology in fundoscopic examination, optical coherence tomography (OCT) revealed a progressive thinning of the retina from 3 months onwards. Cone but not rod photoreceptor loss was observed in 3-month-old diabetic mice. Severe impairment of synaptic connectivity at the outer plexiform layer (OPL) was detected in 9-month old Ins2Akita mice. Specifically, photoreceptor presynaptic ribbons were reduced by 25% and postsynaptic boutons by 70%, although the density of horizontal, rod- and cone-bipolar cells remained similar to non-diabetic controls. Significant reductions in GABAergic and glycinergic amacrine cells and Brn3a+ retinal ganglion cells were also observed in 9-month old Ins2Akita mice. In conclusion, the Ins2Akita mouse develops cone photoreceptor degeneration and the impairment of synaptic connectivity at the OPL, predominately resulting from the loss of postsynaptic terminal boutons. Our findings suggest that the Ins2Akita mouse is a good model to study diabetic retinal neuropathy

Relatório de Recomendações para o Enfrentamento ao Discurso de Ódio e ao Extremismo no Brasil

O presente relatório é fruto de contribuições coletivas oriundas do “Grupo de Trabalho para apresentação de estratégias de enfrentamento ao discurso de ódio e ao extremismo, e para a proposição de políticas públicas em direitos humanos sobre o tema”, instituído pela Portaria nº 130, de 23 de fevereiro de 2023, do Ministério dos Direitos Humanos e da Cidadania (MDHC) da República Federativa do Brasil, nos termos das competência estabelecidas pelo Art. 87, parágrafo único, inciso IV, da Constituição Federal. O Grupo de Trabalho (GT) foi instituído pelo Ministro de Estado dos Direitos Humanos e da Cidadania, Silvio Luiz de Almeida, nomeado pelo presidente da república Luiz Inácio Lula da Silva, considerando a necessidade premente de adoção de medidas que propiciem o enfrentamento ao discurso de ódio e ao extremismo que atualmente colocam em risco a democracia e a paz, prejudicam o funcionamento das instituições, produzem vítimas e provocam violentos conflitos sociais. As atividades do Grupo de Trabalho foram realizadas de forma não remunerada, sem o custeio de quaisquer despesas aos participantes, contando com a participação de membros da sociedade civil, Advocacia-Geral da União, Ministérios do Governo Federal e Secretaria de Comunicação Social da Presidência da República. Por meio deste GT, o MDHC contribui pra realizar o objetivo da República Federativa do Brasil descrito no Art. 3º, inciso IV, da Constituição Federal, de “promover o bem de todos, sem preconceitos de origem, raça, sexo, cor, idade e quaisquer outras formas de discriminação“, alinhando-se com o “Plano de Ação sobre Discurso de Ódio” lançado pela Organização das Nações Unidas (ONU) em 2019. Este documento é um passo inicial sobre o discurso de ódio e o extremismo, cuja complexidade e relevância demandarão novos e contínuos esforços para o levantamento de dados, análise dos fenômenos e apresentação de novas propostas. O GT espera que o relatório circule como um documento de reflexão sobre a urgência do enfrentamento ao ódio e ao extremismo no Brasil e que permita ter a prevenção e o cuidado das vítimas no centro das respostas institucionais e políticas