Aging exacerbates the brain inflammatory micro-environment contributing to α-synuclein pathology and functional deficits in a mouse model of DLB/PD

BACKGROUND

Although ɑ-synuclein (ɑ-syn) spreading in age-related neurodegenerative diseases such as Parkinson's disease (PD) and Dementia with Lewy bodies (DLB) has been extensively investigated, the role of aging in the manifestation of disease remains unclear.

METHODS

We explored the role of aging and inflammation in the pathogenesis of synucleinopathies in a mouse model of DLB/PD initiated by intrastriatal injection of ɑ-syn preformed fibrils (pff).

RESULTS

We found that aged mice showed more extensive accumulation of ɑ-syn in selected brain regions and behavioral deficits that were associated with greater infiltration of T cells and microgliosis. Microglial inflammatory gene expression induced by ɑ-syn-pff injection in young mice had hallmarks of aged microglia, indicating that enhanced age-associated pathologies may result from inflammatory synergy between aging and the effects of ɑ-syn aggregation. Based on the transcriptomics analysis projected from Ingenuity Pathway Analysis, we found a network that included colony stimulating factor 2 (CSF2), LPS related genes, TNFɑ and poly rl:rC-RNA as common regulators.

CONCLUSIONS

We propose that aging related inflammation (eg: CSF2) influences outcomes of pathological spreading of ɑ-syn and suggest that targeting neuro-immune responses might be important in developing treatments for DLB/PD.

Neuroinflammation is associated with infiltration of T cells in Lewy body disease and α-synuclein transgenic models

BACKGROUND

α-Synuclein (α-syn) is a pre-synaptic protein which progressively accumulates in neuronal and non-neuronal cells in neurodegenerative diseases such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy. Recent evidence suggests that aberrant immune activation may be involved in neurodegeneration in PD/DLB. While previous studies have often focused on the microglial responses, less is known about the role of the peripheral immune system in these disorders.

METHODS

To understand the involvement of the peripheral immune system in PD/DLB, we evaluated T cell populations in the brains of α-syn transgenic (tg) mice (e.g., Thy1 promoter line 61) and DLB patients.

RESULTS

Immunohistochemical analysis showed perivascular and parenchymal infiltration by CD3+/CD4+ helper T cells, but not cytotoxic T cells (CD3+/CD8+) or B cells (CD20+), in the neocortex, hippocampus, and striatum of α-syn tg mice. CD3+ cells were found in close proximity to the processes of activated astroglia, particularly in areas of the brain with significant astrogliosis, microgliosis, and expression of pro-inflammatory cytokines. In addition, a subset of CD3+ cells co-expressed interferon γ. Flow cytometric analysis of immune cells in the brains of α-syn tg mice revealed that CD1d-tet+ T cells were also increased in the brains of α-syn tg mice suggestive of natural killer T cells. In post-mortem DLB brains, we similarly detected increased numbers of infiltrating CD3+/CD4+ T cells in close proximity with blood vessels.

CONCLUSION

These results suggest that infiltrating adaptive immune cells play an important role in neuroinflammation and neurodegeneration in synucleinopathies and that modulating peripheral T cells may be a viable therapeutic strategy for PD/DLB.

Host Resistance to pulmonary Mycobacterium tuberculosis infection requires CD153 expression

Mycobacterium tuberculosis infection (Mtb) is the leading cause of death due to a single infectious agent and is among the top ten causes of all human deaths worldwide. CD4 T cells are essential for resistance to Mtb infection, and for decades it has been thought that IFNγ production is the primary mechanism of CD4 T-cell-mediated protection. However, IFNγ responses do not correlate with host protection, and several reports demonstrate that additional anti-tuberculosis CD4 T-cell effector functions remain unaccounted for. Here we show that the tumour-necrosis factor (TNF) superfamily molecule CD153 (encoded by the gene Tnfsf8) is required for control of pulmonary Mtb infection by CD4 T cells. CD153-deficient mice develop high pulmonary bacterial loads and succumb early to Mtb infection. Reconstitution of T-cell-deficient hosts with Tnfsf8−/− CD4 T cells, similar to Ifng−/− CD4 T cells, fails to rescue mice from early mortality. In Mtb-infected non-human primates, Mtb-specific CD153-expressing CD4 T cells inversely correlates with bacterial loads in granulomas. In Mtb-infected humans, CD153 defines a subset of highly polyfunctional Mtb-specific CD4 T cells that are much more abundant in individuals with latent Mtb infection compared to those with active tuberculosis. Thus, CD153 is a major immune mediator of host protection against pulmonary Mtb infection and CD4 T cells are one important source of this molecule.

Characterization of a novel anti-CD20 StradobodyTM with potent in vitro anti-tumor activity (TUM7P.935)

Despite the efficacy of anti-CD20 mAb in the treatment of B-cell malignancies, a proportion of patients are non-responsive or relapse after mAb therapy. Therefore, developing more effective mAbs represents a major area of interest. In this study, we assessed a novel anti-CD20 antibody (stradobodyTM from Gliknik Inc.) consisting of an unmodified Fab sequence and a multimerized Fc domain. In vitro, the anti-CD20 stradobodyTM mediates significantly enhanced inhibition of cell proliferation on select B lymphoma cell lines relative to the unmodified anti-CD20 mAb. In addition, B lymphoma cell lines exhibit increased susceptibility to Complement Dependent cytotoxicity in the presence of a low concentration of the anti-CD20 stradobodyTM. However, anti-CD20 stradobodyTM did not elicit enhanced anti-tumor efficacy in vivo in a Raji-scid xenograft model, in comparison with unmodified anti-CD20 mAb. This discrepancy of in vitro and in vivo anti-tumor efficacy of anti-CD20 stradobodyTM might be attributable to less avidity of the modified human Fc domain to the murine receptors compared with human receptors and highlights the challenges with validating novel targeted mAb therapeutics in vivo.

Antitumor effects of anti-CD137 mAb are influenced by Fc: Fcγ receptor interactions (156.5)

In various preclinical models, agonist antibodies directed against CD137 (4-1BB) enhance the antitumor immunity. However, the contribution of the Fc:Fc receptor interactions to the process of anti-CD137 mediated tumor rejection is unknown. In this study, we provide early evidence that treatment of tumor bearing mice lacking all activating Fcγ receptors (Fcγ chain deficient mice) with the anti-CD137 mAb, 4-1BB2A, improves the survival compared to wild type mice. When Fcγ chain deficient mice and wild type are challenged with EL4E7 tumor cells, tumors were allowed to grow to an approximate size of 10mm by day 7 or 12mm by day 10. When the mice are treated with anti-CD137 mAb, the Fcγ chain deficient mice had increased survival compared to wild type mice even bearing ten day established tumors. Similarly, improved survival is seen in FcγRIII deficient mice bearing ten day established tumors after treatment with anti-CD137 mAb. While still preliminary, our observations suggest that strategies to modify Fc:FcR interactions may improve the therapeutic efficacy of anti-CD137 based cancer immunotherapy.

CD137 promotes proliferation and survival of human B cell (34.14)

CD137 (4-1BB) mediated co-stimulation plays an important role in directing the fate of antigen stimulated T cells and NK cells, yet its role on B cell function is currently unknown. The goal of our study was first to evaluate which external signals regulate CD137 expression on human B cells and second to define the biological effect of CD137-mediated co-stimulation on human B cells. Flow cytometric analysis was used to evaluate cell surface expression of CD137. Cell proliferation was assessed by 3H-TdR incorporation and CFSE dilution assay. Cell apoptosis was determined by Annexin V and 7-AAD staining. Here we report that CD137 is expressed on human B cells stimulated with anti-Ig. CD137 expression is enhanced by CD40 ligation and IFN-γ, and is inhibited by IL-4 and IL-10. The expression of CD137 on activated human B cells is functionally relevant, as engagement with its ligand at the time of activation stimulates B cell proliferation. Furthermore, CD137 stimulation enhances B cell survival which is associated with expression of the anti-apoptotic proteins Bcl-xl and Mcl-1. Our study demonstrates a direct role for CD137-mediated co-stimulation in defining the fate of antigen-stimulated human B cells.