Liesbet Peeters

Circulating Follicular Regulatory T Cells Are Defective in Multiple Sclerosis.

Follicular regulatory T cells (TFR) have been extensively characterized in mice and participate in germinal center responses by regulating the maturation of B cells and production of (auto)antibodies. We report that circulating TFR are phenotypically distinct from tonsil-derived TFR in humans. They have a lower expression of follicular markers, and display a memory phenotype and lack of high expression of B cell lymphoma 6 and ICOS. However, the suppressive function, expression of regulatory markers, and FOXP3 methylation status of blood TFR is comparable with tonsil-derived TFR. Moreover, we show that circulating TFR frequencies increase after influenza vaccination and correlate with anti-flu Ab responses, indicating a fully functional population. Multiple sclerosis (MS) was used as a model for autoimmune disease to investigate alterations in circulating TFR. MS patients had a significantly lower frequency of circulating TFR compared with healthy control subjects. Furthermore, the circulating TFR compartment of MS patients displayed an increased proportion of Th17-like TFR. Finally, TFR of MS patients had a strongly reduced suppressive function compared with healthy control subjects. We conclude that circulating TFR are a circulating memory population derived from lymphoid resident TFR, making them a valid alternative to investigate alterations in germinal center responses in the context of autoimmune diseases, and TFR impairment is prominent in MS.

Cytomegalovirus infection exacerbates autoimmune mediated neuroinflammation

Cytomegalovirus (CMV) is a latent virus which causes chronic activation of the immune system. Here, we demonstrate that cytotoxic and pro-inflammatory CD4+CD28null T cells are only present in CMV seropositive donors and that CMV-specific Immunoglobulin (Ig) G titers correlate with the percentage of these cells. In vitro stimulation of peripheral blood mononuclear cells with CMVpp65 peptide resulted in the expansion of pre-existing CD4+CD28null T cells. In vivo, we observed de novo formation, as well as expansion of CD4+CD28null T cells in two different chronic inflammation models, namely the murine CMV (MCMV) model and the experimental autoimmune encephalomyelitis (EAE) model for multiple sclerosis (MS). In EAE, the percentage of peripheral CD4+CD28null T cells correlated with disease severity. Pre-exposure to MCMV further aggravated EAE symptoms, which was paralleled by peripheral expansion of CD4+CD28null T cells, increased splenocyte MOG reactivity and higher levels of spinal cord demyelination. Cytotoxic CD4+ T cells were identified in demyelinated spinal cord regions, suggesting that peripherally expanded CD4+CD28null T cells migrate towards the central nervous system to inflict damage. Taken together, we demonstrate that CMV drives the expansion of CD4+CD28null T cells, thereby boosting the activation of disease-specific CD4+ T cells and aggravating autoimmune mediated inflammation and demyelination.

Cytotoxic CD4+ T Cells Drive Multiple Sclerosis Progression

Multiple sclerosis (MS) is the leading cause of chronic neurological disability in young adults. The clinical disease course of MS varies greatly between individuals, with some patients progressing much more rapidly than others, making prognosis almost impossible. We previously discovered that cytotoxic CD4+ T cells (CD4+ CTL), identified by the loss of CD28, are able to migrate to sites of inflammation and that they contribute to tissue damage. Furthermore, in an animal model for MS, we showed that these cells are correlated with inflammation, demyelination, and disability. Therefore, we hypothesize that CD4+ CTL drive progression of MS and have prognostic value. To support this hypothesis, we investigated whether CD4+ CTL are correlated with worse clinical outcome and evaluated the prognostic value of these cells in MS. To this end, the percentage of CD4+CD28null T cells was measured in the blood of 176 patients with relapsing-remitting MS (=baseline). Multimodal evoked potentials (EP) combining information on motoric, visual, and somatosensoric EP, as well as Kurtzke expanded disability status scale (EDSS) were used as outcome measurements at baseline and after 3 and 5 years. The baseline CD4+CD28null T cell percentage is associated with EP (P = 0.003, R2 = 0.28), indicating a link between these cells and disease severity. In addition, the baseline CD4+CD28null T cell percentage has a prognostic value since it is associated with EP after 3 years (P = 0.005, R2 = 0.29) and with EP and EDSS after 5 years (P = 0.008, R2 = 0.42 and P = 0.003, R2 = 0.27). To the best of our knowledge, this study provides the first direct link between the presence of CD4+ CTL and MS disease severity, as well as its prognostic value. Therefore, we further elaborate on two important research perspectives: 1° investigating strategies to block or reverse pathways in the formation of these cells resulting in new treatments that slow down MS disease progression, 2° including immunophenotyping in prediction modeling studies to aim for personalized medicine.

The challenge of molecular testing for clinical trials in advanced non-small cell lung cancer patients: Analysis of a prospective database

OBJECTIVES Molecular testing has become important in the biomarker program of clinical trials for advanced non-small lung cancer (NSCLC). These tissue samples often have to be analyzed in a central laboratory. We evaluated the turnaround time and possible delay in start of therapy in this process and how often testing resulted in inclusion in a clinical trial. METHODS We reviewed our prospective database on all molecular testing cases for clinical trial suitability in patients with advanced NSCLC between March 1, 2011 and October 31, 2014. RESULTS 250 patients were considered for biomarker-driven trials. Twenty-three cases did not have further analysis and 20 patients had failure of central biomarker analysis. Results were obtained for 207 (83%) patients. In 91 of 227 (40%) samples sent, a biomarker of interest was documented. This led to 34 (15%) clinical trial inclusions. The mean waiting time between informed consent and request for tissue sections from the pathology lab and receipt of biomarker result from central lab was 24.4 (SD 13.7) calendar days. CONCLUSION While molecular biomarker testing is crucial in many NSCLC trials, our results show that waiting times for central laboratory analysis can cause an important delay in treatment initiation, and even ineligibility for the trial(s) under consideration. Start of therapy based on properly validated local testing, with a posteriori central biomarker testing to guarantee the integrity of the trial, would be more rewarding for quite some patients.

Fair data for next-generation management of multiple sclerosis

Multiple sclerosis (MS) is a progressive demyelinating and degenerative disease of the central nervous system with symptoms depending on the disease type and the site of lesions and is featured by heterogeneity of clinical expressions and responses to treatment strategies. An individualized clinical follow-up and multidisciplinary treatment is required. Transforming the population-based management of today into an individualized, personalized and precision-level management is a major goal in research. Indeed, a complex and unique interplay between genetic background and environmental exposure in each case likely determines clinical heterogeneity. To reach insights at the individual level, extensive amount of data are required. Many databases have been developed over the last few decades, but access to them is limited, and data are acquired in different ways and differences in definitions and indexing and software platforms preclude direct integration. Most existing (inter)national registers and IT platforms are strictly observational or focus on disease epidemiology or access to new disease modifying drugs. Here, a method to revolutionize management of MS to a personalized, individualized and precision level is outlined. The key to achieve this next level is FAIR data.