Evaluation of TLR9 expression on PBMCs and CpG ODN-TLR9 ligation on IFN-α production in SLE patients

Differential expression pattern of Bcl-2 family members in B and T cells in systemic lupus erythematosus and rheumatoid arthritis

OBJECTIVE

This study aimed to evaluate the expression level of anti-apoptotic Bcl-2 family proteins in B and T cells in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in relation to disease activity and the effect of various Bcl-2 family inhibitors (BH3 mimetics) as potential treatment.

METHODS

We included 14 SLE patients, 12 RA patients, and 13 healthy controls to study anti-apoptotic Bcl-2, Bcl-XL, and Mcl-1 expression and cell survival in different B and T cell subsets using stimulation assays and intracellular flow cytometry. Effect of various BH3 mimetics was assessed by cell viability analyses.

RESULTS

In SLE, significant differences in Bcl-2 family members were confined to the B cell compartment with decreased induction of Bcl-XL (p ≤ 0.05) and Mcl-1 (p ≤ 0.001) upon CpG stimulation. In RA, we did not observe any differences in expression levels of Bcl-2 family proteins. Expression patterns did not correlate with disease activity apart from decreased induction of Mcl-1 in B cells in active SLE. After in vitro stimulation with CpG, plasmablasts were more viable after treatment with three different BH3 mimetics compared to naïve or memory B cells in control and patient cells. After activation, Mcl-1 inhibition was most effective in reducing plasmablast and T cell viability, however, less in patients than controls.

CONCLUSION

Our study provides evidence for the increased differential expression pattern of Bcl-2 family members in B and T cell subsets of patients with SLE compared to controls. Tested BH3 mimetics showed higher efficacy in controls compared to both autoimmune diseases, though nonsignificant due to low patient numbers.

DNA-Dependent Interferon Induction and Lung Inflammation in Bordetella pertussis Infection

Pertussis, caused by Bordetella pertussis, is a resurgent respiratory disease but the molecular mechanisms underlying pathogenesis are poorly understood. We recently showed the importance of type I and type III interferon (IFN) induction and signaling for the development of lung inflammation in B. pertussis-infected mouse models. Classically, these IFNs are induced by signaling through a variety of pattern recognition receptors (PRRs) on host cells. Here, we found that the PRR signaling adaptor molecules MyD88 and TRIF contribute to IFN induction and lung inflammatory pathology during B. pertussis infection. However, the PRRs Toll-like receptors (TLR) 3 and TLR4, which signal through TRIF and MyD88, respectively, played no role in IFN induction. Instead, the DNA-sensing PRRs, TLR9 and STING, were important for induction of type I/III IFN and promotion of inflammatory pathology, indicating that DNA is a major inducer of lung IFN responses in B. pertussis infection. These results increase our understanding of this host-pathogen interaction and identify potential targets for host-directed therapies to reduce B. pertussis-mediated pathology.

Ancestry-based differences in the immune phenotype are associated with lupus activity

Systemic lupus erythematosus (SLE) affects 1 in 537 Black women, which is >2-fold more than White women. Black patients develop the disease at a younger age, have more severe symptoms, and have a greater chance of early mortality. We used a multiomics approach to uncover ancestry-associated immune alterations in patients with SLE and healthy controls that may contribute biologically to disease disparities. Cell composition, signaling, epigenetics, and proteomics were evaluated by mass cytometry; droplet-based single-cell transcriptomics and proteomics; and bead-based multiplex soluble mediator levels in plasma. We observed altered whole blood frequencies and enhanced activity in CD8+ T cells, B cells, monocytes, and DCs in Black patients with more active disease. Epigenetic modifications in CD8+ T cells (H3K27ac) could distinguish disease activity level in Black patients and differentiate Black from White patient samples. TLR3/4/7/8/9-related gene expression was elevated in immune cells from Black patients with SLE, and TLR7/8/9 and IFN-α phospho-signaling and cytokine responses were heightened even in immune cells from healthy Black control patients compared with White individuals. TLR stimulation of healthy immune cells recapitulated the ancestry-associated SLE immunophenotypes. This multiomic resource defines ancestry-associated immune phenotypes that differ between Black and White patients with SLE, which may influence the course and severity of SLE and other diseases.

Advances in the mechanisms and applications of inhibitory oligodeoxynucleotides against immune-mediated inflammatory diseases

Inhibitory oligodeoxynucleotides (ODNs) are short single-stranded DNA, which capable of folding into complex structures, enabling them to bind to a large variety of targets. With appropriate modifications, the inhibitory oligodeoxynucleotides exhibited many features of long half-life time, simple production, low toxicity and immunogenicity. In recent years, inhibitory oligodeoxynucleotides have received considerable attention for their potential therapeutic applications in immune-mediated inflammatory diseases (IMIDs). Inhibitory oligodeoxynucleotides could be divided into three categories according to its mechanisms and targets, including antisense ODNs (AS-ODNs), DNA aptamers and immunosuppressive ODNs (iSup ODNs). As a synthetic tool with immunomodulatory activity, it can target RNAs or proteins in a specific way, resulting in the reduction, increase or recovery of protein expression, and then regulate the state of immune activation. More importantly, inhibitory oligodeoxynucleotides have been used to treat immune-mediated inflammatory diseases, including inflammatory disorders and autoimmune diseases. Several inhibitory oligodeoxynucleotide drugs have been developed and approved on the market already. These drugs vary in their chemical structures, action mechanisms and cellular targets, but all of them could be capable of inhibiting excessive inflammatory responses. This review summarized their chemical modifications, action mechanisms and applications of the three kinds of inhibitory oligodeoxynucleotidesin the precise treatment of immune-mediated inflammatory diseases.

Preclinical evaluation of WVE-004, aninvestigational stereopure oligonucleotide forthe treatment of C9orf72-associated ALS or FTD

A large hexanucleotide (G₄C₂) repeat expansion in the first intronic region of C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Several mechanisms have been proposed to explain how the repeat expansion drives disease, and we hypothesize that a variant-selective approach, in which transcripts affected by the repeat expansion are preferentially decreased, has the potential to address most of them. We report a stereopure antisense oligonucleotide, WVE-004, that executes this variant-selective mechanism of action. WVE-004 dose-dependently and selectively reduces repeat-containing transcripts in patient-derived motor neurons carrying a C9orf72-repeat expansion, as well as in the spinal cord and cortex of C9 BAC transgenic mice. In mice, selective transcript knockdown was accompanied by substantial decreases in dipeptide-repeat proteins, which are pathological biomarkers associated with the repeat expansion, and by preservation of healthy C9orf72 protein expression. These in vivo effects were durable, persisting for at least 6 months. These data support the advancement of WVE-004 as an investigational stereopure antisense oligonucleotide targeting C9orf72 for the treatment of C9orf72-associated ALS or FTD.

Immunogenetic Relationship of HLA-G 14 bp Insertion/Deletion Polymorphism and Toll-Like Receptor 9 with Systemic Lupus Erythematosus in Egyptian Patients: A Case-Control Study

Introduction

The level of expression of the immunoregulatory human leukocyte antigen-G (HLA-G) has been suggested to play a role in the immunopathogenesis of systemic lupus erythematosus (SLE). A 14 bp insertion/deletion (ins/del) polymorphism in the 3ˊuntranslated region of HLA-G gene may influence the level of expression. The role of Toll-like receptor 9 (TLR9) in the pathogenesis of SLE has been highlighted. Data among Egyptian patients are quite limited.

Purpose

To detect the association of HLA-G 14 bp ins/del gene polymorphism with the susceptibility to SLE and to correlate TLR9 serum level with disease activity among Egyptian patients.

Patients and Methods

A case-control study that included 102 SLE female patients and 102 healthy matched volunteers as controls was carried out. Disease activity in patients was determined using the modified Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). HLA-G 14 bp ins/del genotype was detected by polymerase chain reaction (PCR). TLR9 serum level was estimated using enzyme-linked immunosorbent assay (ELISA) technique.

Results

The ins/ins genotype was significantly increased among SLE patients compared to healthy subjects (58.8% vs 9.8%; odds ratio [OR] = 11.79, P < 0.001). The 14 bp ins allele was significantly more frequent in SLE patients than in healthy subjects (65.7% vs 27.9%, respectively) and significantly associated with an increased risk of SLE (OR 4.94, P < 0.001). The mean TLR9 serum level showed a significant increase in SLE patients compared to healthy subjects (397.04±137.86 vs 195.22±45.14 ng/L, p < 0.001) and was significantly associated with disease activity as well as to patients’ HLA-G genotypes (p < 0.001).

Conclusion

Among Egyptian population, HLA-G 14 bp ins/ins homozygous genotype and ins allele may constitute a potential risk for SLE susceptibility, while TLR9 serum level is significantly associated with disease activity.

Impaired Innate Immunity in Pediatric Patients Type 1 Diabetes-Focus on Toll-like Receptors Expression

Type 1 diabetes (DM1) is classified as an autoimmune disease. An uncontrolled response of B and T lymphocytes to the body's own tissues develops in the absence of immune tolerance. The main aim of the study was to evaluate the effect of the duration of type 1 diabetes in children on the expression of TLR receptors and the relationship with the parameters of glycemic control in patients. As a result, we showed significant differences in the level of TLR2, TLR4 and TLR9 expression in patients with DM1 in the early stage of the disease and treated chronically compared to the healthy group. Additionally, in this study, we found that the numbers of CD19+ B cells, CD3+ CD4+, CD3+ CD8+ T cells and NK cells are different for newly diagnosed DM1 individuals, patients receiving chronic treatment and for healthy controls, indicating an important role of these cells in killing pancreatic beta cells. Moreover, higher levels of IL-10 in patients with newly diagnosed DM1 have also been found, confirming the reports found in the literature.

Low-dose 17α-ethinyl estradiol (EE) exposure exacerbates lupus renal disease and modulates immune responses to TLR7/9 agonists in genetically autoimmune-prone mice

Estrogens have been shown to regulate the immune system and modulate multiple autoimmune diseases. 17α-ethinyl estradiol (EE), a synthetic analog of 17β-estradiol, is prescribed commonly and found in oral contraceptives and hormone replacement therapies. Surprisingly, few studies have investigated the immunoregulatory effects of exposure to EE, especially in autoimmunity. In this study, we exposed autoimmune-prone female MRL/lpr mice to a human-relevant dose of EE through the oral route of exposure. Since lupus patients are prone to infections, groups of mice were injected with viral (Imiquimod, a TLR7 agonist) or bacterial (ODN 2395, a TLR9 agonist) surrogates. We then evaluated autoimmune disease parameters, kidney disease, and response to in vivo TLR7/9 pathogenic signals. EE-exposed mice had increased proteinuria as early as 7 weeks of age. Proteinuria, blood urea nitrogen, and glomerular immune complex deposition were also exacerbated when compared to controls. Production of cytokines by splenic leukocytes were altered in EE-exposed mice. Our study shows that oral exposure to EE, even at a very low dose, can exacerbate azotemia, increase clinical markers of renal disease, enhance glomerular immune complex deposition, and modulate TLR7/9 cytokine production in female MRL/lpr mice. This study may have implications for EE-exposure risk for genetically lupus-prone individuals.

CpG-ODN-mediated TLR9 innate immune signalling and calcium dyshomeostasis converge on the NFκB inhibitory protein IκBβ to drive IL1α and IL1β expression

Sterile inflammation contributes to many pathological states associated with mitochondrial injury. Mitochondrial injury disrupts calcium homeostasis and results in the release of CpG-rich mitochondrial DNA. The role of CpG-stimulated TLR9 innate immune signalling and sterile inflammation is well studied; however, how calcium dyshomeostasis affects this signalling is unknown. Therefore, we interrogated the relationship beτween intracellular calcium and CpG-induced TLR9 signalling in murine macrophages. We found that CpG-ODN-induced NFκB-dependent IL1α and IL1β expression was significantly attenuated by both calcium chelation and calcineurin inhibition, a finding mediated by inhibition of degradation of the NFκB inhibitory protein IκBβ. In contrast, calcium ionophore exposure increased CpG-induced IκBβ degradation and IL1α and IL1β expression. These results demonstrate that through its effect on IκBβ degradation, increased intracellular Ca²⁺ drives a pro-inflammatory TLR9-mediated innate immune response. These results have implications for the study of innate immune signalling downstream of mitochondrial stress and injury.

Oligodeoxynucleotides ODN 2006 and M362 Exert Potent Adjuvant Effect through TLR-9/-6 Synergy to Exaggerate Mammaglobin-A Peptide Specific Cytotoxic CD8+T Lymphocyte Responses against Breast Cancer Cells

Mammaglobin-A (MamA) is overexpressed in 40–80% of all human breast cancers. Recent phase I clinical trials of the MamA DNA vaccine showed encouraging safety outcomes. However, this vaccine elicited only a modest increase in MamA specific CD8+T lymphocyte (CTL) activation. As vaccine adjuvants play a critical role in enhancing the immunotherapeutic efficiency of vaccines, we tested the potential role of three synthetic CpG oligodeoxynucleotides (ODN2216—class A ODN, ODN2006—class B ODN, and ODN M362—class C ODN) to further enhance MamA specific CTL responses. Towards this, naïve CD8+T cells were obtained from healthy HLA-A2+ human donors. The HLA-A2 specific immunodominant epitope of MamA, MamA2.1 (LIYDSSLCDL), was utilized to activate naïve CD8+T cells. The THP-1 (HLA-A2+) cells were used as antigen presenting cells to stimulate naïve CD8+T cells along with (or without) co-treatment of various ODNs mentioned above. Activation of naïve CD8+T cells with the MamA2.1 peptide along with ODNs demonstrated enhanced MamA specific CTL mediated cytotoxicity on AU565 (HLA-A⁺/MamA⁺) breast cancer cells following co-treatment with ODN2006 and M362 compared to ODN2216 or MamA2.1 peptide alone. However, no significant cytotoxicity was noted upon treatment of MamA2.1 activated CTLs on MCF7 (HLA-A⁺/MamA⁻) cells, suggesting that the activation of CTLs is specific to the MamA antigen. Functional characterization studies demonstrated specific IL-12 mediated cross-talk between TLR-6 and -9 in THP-1 cells following stimulation with ODN2006 and M362, which was critical for the final cytotoxic activation of CD8+T lymphocytes. Based on these data, we conclude that ODN2006 and ODN M362 exerted a strong adjuvant effect through induction of the initial innate immune response through TLR9 upregulation followed by enhanced MamA specific CTL dependent adaptive immune responses. Our current data provide evidence for the application of Class-B/-C-CpG-ODNs as potential vaccine adjuvants towards enhancing the success of MamA based breast cancer vaccination.

Below the surface: The inner lives of TLR4 and TLR9

TLRs are a class of pattern recognition receptors (PRRs) that detect invading microbes by recognizing pathogen-associated molecular patterns (PAMPs). Upon PAMP engagement, TLRs activate a signaling cascade that leads to the production of inflammatory mediators. The localization of TLRs, either on the plasma membrane or in the endolysosomal compartment, has been considered to be a fundamental aspect to determine to which ligands the receptors bind, and which transduction pathways are induced. However, new observations have challenged this view by identifying complex trafficking events that occur upon TLR-ligand binding. These findings have highlighted the central role that endocytosis and receptor trafficking play in the regulation of the innate immune response. Here, we review the TLR4 and TLR9 transduction pathways and the importance of their different subcellular localization during the inflammatory response. Finally, we discuss the implications of TLR9 subcellular localization in autoimmunity.

Association of toll-like receptor 9 expression with prognosis of systemic lupus erythematosus

The current study assessed the association between toll-like receptor 9 (TLR9) and systemic lupus erythematosus (SLE) and subsequently determined the predictive value of TLR9 in assessing the prognosis of SLE. A total of 90 newly diagnosed patients with SLE and 49 healthy control subjects were enrolled in the current study. The expression of TLR9 mRNA was measured in whole blood samples from patients and controls. All patients were followed up for ≥2 years and their clinical parameters were recorded. After 2 years, 30 patients were randomly chosen from patient subgroups with high (n=20) or low (n=10) TLR9 levels and the expression of TLR9 mRNA were measured again. Cox proportional hazards regression was used to identify the risk factors of SLE prognosis. Patients with SLE and high SLE disease activity exhibited significantly increased TLR9 expression (P<0.05). Persistent proteinuria of >0.5 g/day [hazard ratio (HR), 6.314; 95% confidence interval (CI), 2.858-13.947], C-reactive protein levels (HR, 1.013; 95% CI, 1.007-1.019) and high-TLR9 mRNA expression (HR, 3.852; 95% CI, 1.931-7.684) were independent risk factors of poor prognosis during a 2-year follow-up period, whereas patient treatment with >1 immunosuppressant (HR, 0.374; 95% CI, 0.173-0.808) was a factor indicating favorable prognosis. Furthermore, the expression of TLR9 mRNA remained high in patients with poor prognosis at the end of a 2-year follow-up period but in patients with a favorable prognosis, TLR9 mRNA expression was significantly reduced compared with the levels measured at SLE onset (P<0.0001). Therefore, the expression of TLR9 mRNA in whole blood samples at SLE onset is associated with SLE disease activity and its expression may be used as an indicator of poor prognosis in patients with SLE.

17β-Estradiol and 17α-Ethinyl Estradiol Exhibit Immunologic and Epigenetic Regulatory Effects in NZB/WF1 Female Mice

17α-Ethinyl estradiol (EE), a synthetic analog of natural estrogen 17β-estradiol (E2), is extensively used in hormonal contraceptives and estrogen replacement therapy, and it has also been found in sewage effluents. Given that E2 is a well-known immunomodulator, surprisingly there has been only limited information on the cellular and molecular immunologic consequences of exposure to EE. To address this fundamental gap, we directly compared the effects of EE with E2 on splenic leukocytes of New Zealand Black × New Zealand White F1 progeny (NZB/WF1) mice during the preautoimmune period. We found that EE and E2 have common, as well as distinctive, immunologic effects, with EE exposure resulting in more profound effects. Both EE and E2 increased numbers of splenic neutrophils, enhanced neutrophil serine proteases and myeloperoxidase expression, promoted the production of nitric oxide and monocyte chemoattractant protein-1, and altered adaptive immune T cell subsets. However, activation of splenic leukocytes through the T cell receptor or Toll-like receptor (TLR)4 revealed not only common (IL-10), but also hormone-specific alterations of cytokines (IFNγ, IL-1β, ΤΝFα, IL-2). Furthermore, in EE-exposed mice, TLR9 stimulation suppressed IFNα, in contrast to increased IFNα from E2-exposed mice. EE and E2 regulated common and hormone-specific expression of immune-related genes. Furthermore, EE exposure resulted in more marked alterations in miRNA expression levels than for E2. Only EE was able to reduce global DNA methylation significantly in splenic leukocytes. Taken together, our novel data revealed that EE and E2 exposure confers more similar effects in innate immune system-related cell development and responses, but has more differential regulatory effects in adaptive immune-related cell development and responses.

Molecular mechanisms of glucocorticoid resistance in systemic lupus erythematosus: A review

The treatment of systemic lupus erythematosus (SLE) with glucocorticoids (GCs) is quite effective; however, GC resistance or insensitivity is a major barrier to the treatment of SLE. Therefore, it is necessary to identify the underlying mechanisms that lead to GC resistance. Much evidence shows that the mechanism of GC resistance is very complicated. GC receptor is involved in the main mechanism of GC resistance and was illustrated by a lot of literature. Therefore, this paper focuses on the GC resistance mechanisms of non-glucocorticoids receptor, including P-gp, MIF, TLR9, and Th17 cells. These molecular mechanisms may help diagnose GC resistance and provide an alternative treatment strategy to reverse GC resistance by blocking the underlying mechanisms.

Potential Chronotherapeutic Optimization of Antimalarials in Systemic Lupus Erythematosus: Is Toll-Like Receptor 9 Expression Dependent on the Circadian Cycle in Humans?

Toll-like receptor 9 (TLR9) belongs to the group of endosomal receptors of the innate immune system with the ability to recognize hypomethylated CpG sequences from DNA. There is scarce information about TLR9 expression and its association with the circadian cycle (CC). Different patterns of TLR9 expression are regulated by the CC in mice, with an elevated expression at Zeitgeber time 19 (1:00 a.m.); nevertheless, we still need to corroborate this in humans. In systemic lupus erythematosus (SLE), the inhibitory effect of chloroquine (CQ) on TLR9 is limited. TLR9 activation has been associated with the presence of some autoantibodies: anti-Sm/RNP, anti-histone, anti-Ro, anti-La, and anti-double-stranded DNA. Treatment with CQ for SLE has been proven to be useful, in part by interfering with HLA-antigen coupling and with TLR9 ligand recognition. Studies have shown that TLR9 inhibitors such as antimalarial drugs are able to mask TLR9-binding sites on nucleic acids. The data presented here provide the basic information that could be useful for other clinical researchers to design studies that will have an impact in achieving a chronotherapeutic effect by defining the ideal time for CQ administration in SLE patients, consequently reducing the pathological effects that follow the activation of TLR9.

Immune activation by nucleic acids: A role in pregnancy complications

Cell-free self-DNA or RNA may induce an immune response by activating specific sensing receptors. During pregnancy, placental nucleic acids present in the maternal circulation further activate these receptors due to the presence of unmethylated CpG islands. A higher concentration of cell-free foetal DNA is associated with pregnancy complications and a higher risk for foetal rejection. Cell-free foetal DNA originates from placental trophoblasts. It appears in different forms: free, bound to histones in nucleosomes, in neutrophil extracellular traps (NETs) and in extracellular vesicles (EVs). In several pregnancy complications, cell-free foetal DNA triggers the production of proinflammatory cytokines, and this production results in a cellular and humoral immune response. This review discusses preeclampsia, systemic lupus erythematosus, foetal growth restriction, gestational diabetes, rheumatoid arthritis and obesity in pregnancy from an immunological point of view and closely examines the different pathways that result in maternal inflammation. Understanding the role of cell-free nucleic acids, as well as the biogenesis of NETs and EVs, will help us to specify their functions or targets, which seem to be important in pregnancy complications. It is still not clear whether higher concentrations of cell-free nucleic acids in the maternal circulation are the cause or consequence of various complications. Therefore, further clinical studies and, even more importantly, animal experiments that focus on the involved immunological pathways are needed.

Our Environment Shapes Us: The Importance of Environment and Sex Differences in Regulation of Autoantibody Production

Consequential differences exist between the male and female immune systems’ ability to respond to pathogens, environmental insults or self-antigens, and subsequent effects on immunoregulation. In general, females when compared with their male counterparts, respond to pathogenic stimuli and vaccines more robustly, with heightened production of antibodies, pro-inflammatory cytokines, and chemokines. While the precise reasons for sex differences in immune response to different stimuli are not yet well understood, females are more resistant to infectious diseases and much more likely to develop autoimmune diseases. Intrinsic (i.e., sex hormones, sex chromosomes, etc.) and extrinsic (microbiome composition, external triggers, and immune modulators) factors appear to impact the overall outcome of immune responses between sexes. Evidence suggests that interactions between environmental contaminants [e.g., endocrine disrupting chemicals (EDCs)] and host leukocytes affect the ability of the immune system to mount a response to exogenous and endogenous insults, and/or return to normal activity following clearance of the threat. Inherently, males and females have differential immune response to external triggers. In this review, we describe how environmental chemicals, including EDCs, may have sex differential influence on the outcome of immune responses through alterations in epigenetic status (such as modulation of microRNA expression, gene methylation, or histone modification status), direct and indirect activation of the estrogen receptors to drive hormonal effects, and differential modulation of microbial sensing and composition of host microbiota. Taken together, an intriguing question develops as to how an individual’s environment directly and indirectly contributes to an altered immune response, dysregulation of autoantibody production, and influence autoimmune disease development. Few studies exist utilizing well-controlled cohorts of both sexes to explore the sex differences in response to EDC exposure and the effects on autoimmune disease development. Translational studies incorporating multiple environmental factors in animal models of autoimmune disease are necessary to determine the interrelationships that occur between potential etiopathological factors. The presence or absence of autoantibodies is not a reliable predictor of disease. Therefore, future studies should incorporate all the susceptibility/influencing factors, coupled with individual genomics, epigenomics, and proteomics, to develop a model that better predicts, diagnoses, and treats autoimmune diseases in a personalized-medicine fashion.

Different interleukin-17-secreting Toll-like receptor+ T-cell subsets are associated with disease activity in multiple sclerosis

Signalling through Toll-like receptors (TLRs) may play a role in the pathogenesis of autoimmune diseases, such as multiple sclerosis (MS). In the present study, the expression of TLR-2, -4 and -9 was significantly higher on CD4⁺ and CD8⁺ T-cells from MS patients compared to healthy individuals. Following in-vitro activation, the proportion of interleukin (IL)-17⁺ and IL-6⁺ CD4⁺ and CD8⁺ T-cells was higher in the patients. In addition, the proportion of IFN-γ-secreting TLR⁺ CD8⁺ T-cells was increased in MS patients. Among different IL-17⁺ T-cell phenotypes, the proportion of IL-17⁺ TLR⁺ CD4⁺ and CD8⁺ T-cells producing IFN-γ or IL-6 were positively associated with the number of active brain lesions and neurological disabilities. Interestingly, activation of purified CD4⁺ and CD8⁺ T-cells with ligands for TLR-2 (Pam3Csk4), TLR-4 [lipopolysaccharide (LPS)] and TLR-9 [oligodeoxynucleotide (ODN)] directly induced cytokine production in MS patients. Among the pathogen-associated molecular patterns (PAMPs), Pam3Csk4 was more potent than other TLR ligands in inducing the production of all proinflammatory cytokines. Furthermore, IL-6, IFN-γ, IL-17 and granulocyte-macrophage colony-stimulating factor (GM-CSF) levels produced by Pam3Csk4-activated CD4⁺ cells were directly associated with disease activity. A similar correlation was observed with regard to IL-17 levels released by Pam3Csk4-stimulated CD8⁺ T-cells and clinical parameters. In conclusion, our data suggest that the expansion of different T helper type 17 (Th17) phenotypes expressing TLR-2, -4 and -9 is associated with MS disease activity, and reveals a preferential ability of TLR-2 ligand in directly inducing the production of cytokines related to brains lesions and neurological disabilities.