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. 2018 Jul 1;141(7):2066-2082.
doi: 10.1093/brain/awy151.

The Compartmentalized Inflammatory Response in the Multiple Sclerosis Brain Is Composed of Tissue-Resident CD8+ T Lymphocytes and B Cells

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Free PMC article

The Compartmentalized Inflammatory Response in the Multiple Sclerosis Brain Is Composed of Tissue-Resident CD8+ T Lymphocytes and B Cells

Joana Machado-Santos et al. Brain. .
Free PMC article

Abstract

Multiple sclerosis is an inflammatory demyelinating disease in which active demyelination and neurodegeneration are associated with lymphocyte infiltrates in the brain. However, so far little is known regarding the phenotype and function of these infiltrating lymphocyte populations. In this study, we performed an in-depth phenotypic characterization of T and B cell infiltrates in a large set of multiple sclerosis cases with different disease and lesion stages and compared the findings with those seen in inflammatory, non-inflammatory and normal human controls. In multiple sclerosis lesions, we found a dominance of CD8+ T cells and a prominent contribution of CD20+ B cells in all disease courses and lesion stages, including acute multiple sclerosis cases with very short disease duration, while CD4+ T cells were sparse. A dominance of CD8+ T cells was also seen in other inflammatory controls, such as Rasmussen's encephalitis and viral encephalitis, but the contribution of B cells in these diseases was modest. Phenotypic analysis of the CD8+ T cells suggested that part of the infiltrating cells in active lesions proliferate, show an activated cytotoxic phenotype and are in part destroyed by apoptosis. Further characterization of the remaining cells suggest that CD8+ T cells acquire features of tissue-resident memory cells, which may be focally reactivated in active lesions of acute, relapsing and progressive multiple sclerosis, while B cells, at least in part, gradually transform into plasma cells. The loss of surface molecules involved in the egress of leucocytes from inflamed tissue, such as S1P1 or CCR7, and the upregulation of CD103 expression may be responsible for the compartmentalization of the inflammatory response in established lesions. Similar phenotypic changes of tissue-infiltrating CD8+ T cells were also seen in Rasmussen's encephalitis. Our data underline the potential importance of CD8+ T lymphocytes and B cells in the inflammatory response in established multiple sclerosis lesions. Tissue-resident T and B cells may represent guardians of previous inflammatory brain disease, which can be reactivated and sustain the inflammatory response, when they are re-exposed to their specific antigen.

Figures

Figure 1
Figure 1
Examples of the inflammatory response in multiple sclerosis lesions. A and B show inflammation in active lesions of acute (A) and secondary progressive multiple sclerosis (B). CD3+ T cells are stained in brown and B cells in blue. T cells are present in the perivascular space and diffusely disperse into the lesion parenchyme. In contrast, B cells accumulate mainly in the perivascular space of large veins, located in the centre of the lesions. C and D show proliferating T cells (C) and B cells (D) expressing PCNA within their nucleus. (E and F) Apoptosis is seen in T cells (asterisk), labelled with CD3 and identified by the fragmented and condensed nucleus (E) or by the positivity for DNA-fragmentation (TUNEL staining; F). (G) Rare CD3+ T cells, mainly located in the lesion parenchyme show nuclear expression of the transcription factor NFAT (blue nucleus; asterisk) in comparison to an adjacent T cell without nuclear reactivity. (H) Clusters of CD8+ T cells (blue) containing GZMB-positive cytoplasmic granules (brown) as a sign of cytotoxic differentiation are seen in the lesions. (I to L) Perivenous inflammatory cuffs contain only few CD4+ T cells (I), while the majority of cells are CD8+ (J and K) or CD20+ (L). (M and N) A subset of infiltrating lymphocytes express the chemokine receptor CCR5. (O) Only a small proportion of lymphocytes express the exhaustion marker PD1. (P) In addition to T and B cells a substantial number of immunoglobulin-containing plasma cells is seen in the infiltrates. Scale bars = 100 µm. Images for colourblind readers can be found in Supplementary Fig. 5.
Figure 2
Figure 2
Characterization of the lymphocyte subsets in multiple sclerosis lesions in comparison to inflammatory and non-inflammatory controls. (AD) The inflammatory response in the lesions is dominated by CD3+/CD8+ T lymphocytes, while the contribution of CD4+ T cells is minor; the number of CD20+ B cells is highly variable between lesions and cases; while T cells are similar in number and distribution between multiple sclerosis and inflammatory controls, B cells are more selectively enriched in multiple sclerosis lesions in comparison to other inflammatory controls; T and B cell infiltrates are very sparse in non-inflammatory controls. (EL) A more detailed analysis shows that T and B cells are significantly more numerous in the lesions of acute and relapsing multiple sclerosis in comparison to those in progressive multiple sclerosis (EH). The stars shown in the acute multiple sclerosis and relapsing-remitting multiple sclerosis (RRMS) data indicate those patients, who have not been treated with corticosteroids. In addition, active lesions show the highest degree of inflammation, followed by slowly expanding lesions (SEL) and inactive lesions (IL). Significance levels: *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.
Figure 3
Figure 3
Distribution of leucocytes within different multiple sclerosis lesion areas. (A) Schematic graph of an active multiple sclerosis lesion with a central large inflamed vein, a demyelinated tissue area, containing macrophages with different stages of myelin degradation (green area) and a rim of initial tissue injury (grey zone) characterized by microglia activation, oligodendrocyte injury (loss of myelin associated glycoprotein) and oligodendrocyte apoptosis (‘prephagocytic’ lesion areas; Barnett and Prineas, 2004). The highest density of lymphocytes is seen in the perivascular space of the central vein and most of the B cells in the lesion are present at this site. T cells also diffusely infiltrate the lesion parenchyma (green area). They are also present, but in low numbers, at the site of initial demyelination (grey area; Marik et al., 2007). (BH) Perivascular (PVA) versus diffuse parenchymal distribution of lymphocyte subsets in multiple sclerosis lesions. When quantification is based on the area of the entire lesion (mm2) most leucocyte subsets (CD3, CD8α, CD8β, CCR5) are present in both compartments without significant preference. Dominant localization in the perivascular space is seen for B cells (CD20) and to a lower extent for CD4+ T cells. In contrast CD103+ T cells show a trend towards accumulation in the lesion parenchyma. Images for colourblind readers can be found in Supplementary Fig. 5. RRMS = relapsing-remitting multiple sclerosis.
Figure 4
Figure 4
Phenotypic characterization of CD8+ T lymphocytes in multiple sclerosis lesions from different disease stages in comparison to inflammatory controls. The values are plotted against disease duration; early stage disease includes a case of ADEM with 2 days disease duration (filled square), of human autoimmune encephalomyelitis (h-AE) with 1.7 months disease duration (open square), of acute multiple sclerosis (disease duration 0.2 to 7 months; filled circles) and of Rasmussen’s encephalitis (open circles, disease duration: 1.4 to 93.4 months). Cases of progressive multiple sclerosis are indicated by filled triangles (disease duration of 30 to 492 months). Overall there is a decrease of the inflammatory reaction with disease duration. T cell activation markers (proliferation, NFAT and GZMB expression and apoptosis) are very low in patients with progressive multiple sclerosis, but even in these patients small clusters of activated CD8+ T cells are present. The dominant CD8+ T cell phenotype in all stages is the CD8α/α-positive cell, showing an inactive (quiescent) phenotype. MS = multiple sclerosis; RRMS = relapsing-remitting multiple sclerosis.
Figure 5
Figure 5
Phenotypic characterization of CD8+ T cells and B cells in multiple sclerosis lesions. (A and B) Only a subset of the CD8α positive cells also express CD8β in a lesion of acute multiple sclerosis. (C and D) CD103 is expressed in a subset of lymphocytes in the lesions; these cells are preferentially located in the lesion parenchyma and less in the perivascular space. (EG) CD69 is expressed in multiple sclerosis lesions in some macrophages (E), in oligodendrocytes and myelin (F) and in some reactive astrocytes (G), while CD3+ cells (blue cells) invariably were negative. (H) In the inflamed mucosa of the tonsil strong CD69 expression is present in a subset of lymphocytes. (IJ) TGF-β is present in multiple sclerosis lesions in reactive astrocytes and endothelial cells, but absent in perivascular or parenchymal lymphocytes. (K and L) IL-10 was found at high levels in plasma cells (K; see also high magnification insert) and in reactive astrocytes in the lesion (L), but not in perivascular or parenchymal lymphocytes (K). (MO) The S1P1 receptor is highly expressed on circulating leucocytes in the vascular lumen (M and N), while perivascular and parenchymal lymphocytes are negative; as described before by others (Van Doorn et al., 2010; Brana et al., 2014) we found S1P1 receptor expression in endothelial cells and reactive astrocytes (N and O). (PT) Phenotypic characterization of cells of the B cell lineage. (PR) An inflammatory infiltrate in a lesion of secondary progressive multiple sclerosis, which mainly contains plasma cells with only few CD20+ B cells. The number of inflammatory cells expressing CD27 is low (P), while there are high numbers of CD38+ cells and immunoglobulin (Ig) containing plasma cells. S shows a B cell (red) rich inflammatory infiltrate double stained with CD27 (green). The CD27 expression in the CD20+ cells (double-labelling shown in yellow) ranges from very strong expression to a more restricted punctate expression. T shows an inflammatory infiltrate in a lesion from secondary progressive multiple sclerosis mainly containing plasma cells, which are double stained for CD38 and the plasma cell marker CD138. Scale bars = 100 µm. Images for colourblind readers can be found in Supplementary Fig. 5.

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References

    1. Alvord EC. Acute disseminated encephalomyelitis and “allergic” neuroencephalopaties. New York, NY: Elsevier; 1970.
    1. Arnason B. Tumour necrosis factor neutralization in MS: a cautionary tale. Int MS J 2011; 17: 63–8. - PubMed
    1. Babbe H, Roers A, Waisman A, Lassmann H, Goebels N, Hohlfeld R., et al. Clonal expansions of CD8(+) T cells dominate the T cell infiltrate in active multiple sclerosis lesions as shown by micromanipulation and single cell polymerase chain reaction. J Exp Med 2000; 192: 393–404. - PMC - PubMed
    1. Barnett MH, Prineas JW. Relapsing and remitting multiple sclerosis: pathology of the newly forming lesion. Ann Neurol 2004; 55: 458–68. - PubMed
    1. Bauer J, Bradl M, Hickley WF, Forss-Petter S, Breitschopf H, Linington C., et al. T-cell apoptosis in inflammatory brain lesions: destruction of T cells does not depend on antigen recognition. Am J Pathol 1998; 153: 715–24. - PMC - PubMed

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