Importance Neuroinflammation appears to be a key modulator of disease progression in amyotrophic lateral sclerosis (ALS) and thereby a promising therapeutic target. The CD4⁺Foxp3⁺regulatory T-cells (Tregs) infiltrating into the central nervous system suppress neuroinflammation and promote the activation of neuroprotective microglia in mouse models of ALS. To our knowledge, the therapeutic association of host Treg expansion with ALS progression has not been studied in vivo. Objective To assess the role of Tregs in regulating the pathophysiology of ALS in humans and the therapeutic outcome of increasing Treg activity in a mouse model of the disease. Design, Setting, and Participants This prospective multicenter human and animal study was performed in hospitals, outpatient clinics, and research institutes. Clinical and function assessment, as well as immunological studies, were undertaken in 33 patients with sporadic ALS, and results were compared with 38 healthy control participants who were consecutively recruited from the multidisciplinary ALS clinic at Westmead Hospital between February 1, 2013, and December 31, 2014. All data analysis on patients with ALS was undertaken between January 2015 and December 2016. Subsequently, we implemented a novel approach to amplify the endogenous Treg population using peripheral injections of interleukin 2/interleukin 2 monoclonal antibody complexes (IL-2c) in transgenic mice that expressed mutant superoxide dismutase 1 (SOD1), a gene associated with motor neuron degeneration. Main Outcomes and Measures In patients with ALS, Treg levels were determined and then correlated with disease progression. Circulating T-cell populations, motor neuron size, glial cell activation, and T-cell and microglial gene expression in spinal cords were determined in SOD1^G93Amice, as well as the association of Treg amplification with disease onset and survival time in mice. Results The cohort of patients with ALS included 24 male patients and 9 female patients (mean [SD] age at assessment, 58.9 [10.9] years). There was an inverse correlation between total Treg levels (including the effector CD45RO⁺subset) and rate of disease progression (R = −0.40,P = .002). Expansion of the effector Treg population in the SOD1^G93Amice was associated with a significant slowing of disease progression, which was accompanied by an increase in survival time (IL-2c–treated mice: mean [SD], 160.6 [10.8] days; control mice: mean [SD], 144.9 [10.6] days;P = .003). Importantly, Treg expansion was associated with preserved motor neuron soma size and marked suppression of astrocytic and microglial immunoreactivity in the spinal cords of SOD1^G93Amice, as well as elevated neurotrophic factor gene expression in spinal cord and peripheral nerves. Conclusions and Relevance These findings establish a neuroprotective effect of Tregs, possibly mediated by suppression of toxic neuroinflammation in the central nervous system. Strategies aimed at enhancing the Treg population and neuroprotective activity from the periphery may prove therapeutically useful for patients with ALS.

Multiple sclerosis (MS) is an autoimmune disease with a genetic component, caused at least in part by aberrant lymphocyte activity. The whole blood mRNA transcriptome was measured for 99 untreated MS patients: 43 primary progressive MS, 20 secondary progressive MS, 36 relapsing remitting MS and 45 age-matched healthy controls. The ANZgene Multiple Sclerosis Genetics Consortium genotyped more than 300 000 SNPs for 115 of these samples. Transcription from genes on translational regulation, oxidative phosphorylation, immune synapse and antigen presentation pathways was markedly increased in all forms of MS. Expression of genes tagging T cells was also upregulated (P < 10⁻¹²) in MS. A T cell gene signature predicts disease state with a concordance index of 0.79 with age and gender as co-variables, but the signature is not associated with clinical course or disability. The ANZgene genome wide association screen identified two novel regions with genome wide significance: one encoding the T cell co-stimulatory molecule, CD40; the other a region on chromosome 12q13-14. The CD40 haplotype associated with increased MS susceptibility has decreased gene expression in MS (P < 0.0007). The second MS susceptibility region includes 17 genes on 12q13-14 in tight linkage disequilibrium. Of these, only 13 are expressed in leukocytes, and of these the expression of one, FAM119B, is much lower in the susceptibility haplotype (P < 10⁻¹⁴). Overall, these data indicate dysregulation of T cells can be detected in the whole blood of untreated MS patients, and supports targeting of activated T cells in therapy for all forms of MS.

We have identified a marked over-representation of transcription factors controlling differentiation of T, B, myeloid and NK cells among the 110 MS genes now known to be associated with multiple sclerosis (MS). To test if the expression of these genes might define molecular subtypes of MS, we interrogated their expression in blood in three independent cohorts of untreated MS (from Sydney and Adelaide) or clinically isolated syndrome (CIS, from San Francisco) patients. Expression of the transcription factors (TF) controlling T and NK cell differentiation, EOMES, TBX21 and other TFs was significantly lower in MS/CIS compared to healthy controls in all three cohorts. Expression was tightly correlated between these TFs, with other T/NK cell TFs, and to another downregulated gene, CCL5. Expression was stable over time, but did not predict disease phenotype. Optimal response to therapy might be indicated by normalization of expression of these genes in blood.

Reports of resurgence in invasive group A streptococcal (GAS) infections come mainly from affluent populations with infrequent exposure to GAS. In the Northern Territory (NT) of Australia, high incidence of invasive GAS disease is secondary to endemic skin infection, serotype M1 clones are rare in invasive infection, the diversity and level of exposure to GAS strains are high, and no particular strains dominate. Expression of a plasminogen-binding GAS M-like protein (PAM) has been associated with skin infection in isolates elsewhere (D. Bessen, C. M. Sotir, T. M. Readdy, and S. K. Hollingshead, J. Infect. Dis. 173: 896-900, 1996), and subversion of the host plasminogen system by GAS is thought to contribute to invasion in animal models. Here, we describe the relationship between plasminogen-binding capacity of GAS isolates, PAM genotype, and invasive capacity in 29 GAS isolates belonging to 25 distinct strains from the NT. In the presence of fibrinogen and streptokinase, invasive isolates bound more plasminogen than isolates from uncomplicated infections ( P ≤ 0.004). Only PAM-positive isolates bound substantial levels of plasminogen by a fibrinogen-streptokinase-independent pathway (direct binding). Despite considerable amino acid sequence variation within the A1 repeat region of PAM where the plasminogen-binding domain maps, the critical lysine residue was conserved.