Jean-Luc Rummens

Compromised CD4+ CD25high regulatory T‐cell function in patients with relapsing‐remitting multiple sclerosis is correlated with a reduced frequency of FOXP3‐positive cells and reduced FOXP3 expression at the single‐cell level

CD4+ CD25high regulatory T cells (Tregs) of patients with relapsing‐remitting (RR) multiple sclerosis (MS), in contrast to those of patients with secondary progressive (SP) MS, show a reduced suppressive function. In this study, we analysed forkhead box P3 (FOXP3) at the single‐cell level in MS patients and controls (healthy individuals and patients with other neurological diseases) by means of intracellular flow cytometry. Our data revealed a reduced number of peripheral blood CD4+ CD25high FOXP3+ T cells and lower FOXP3 protein expression per cell in RR‐MS patients than in SP‐MS patients and control individuals, which was correlated with the suppressive capacity of Tregs in these patients. Interestingly, interferon (IFN)‐β‐treated RR‐MS patients showed restored numbers of FOXP3+ Tregs. Furthermore, a higher percentage of CD4+ CD25high FOXP3+ Tregs in RR‐MS patients, as compared with controls and SP‐MS patients, expressed CD103 and CD49d, adhesion molecules involved in T‐cell recruitment towards inflamed tissues. This was consistent with a significantly increased number of CD27+ CD25high CD4+ T cells in the cerebrospinal fluid (CSF), as compared with peripheral blood, in RR‐MS patients. Taken together, these data show aberrant FOXP3 expression at the single‐cell level correlated with Treg dysfunction in RR‐MS patients. Our results also suggest that Tregs accumulate in the CSF of RR‐MS patients, in an attempt to down‐regulate local inflammation in the central nervous system.

Recovery of Regional but Not Global Contractile Function by the Direct Intramyocardial Autologous Bone Marrow Transplantation Results From a Randomized Controlled Clinical Trial

Background— Recent trials have shown that intracoronary infusion of bone marrow cells (BMCs) improves functional recovery after acute myocardial infarction. However, whether this treatment is effective in heart failure as a consequence of remodeling after organized infarcts remains unclear. In this randomized trial, we assessed the hypothesis that direct intramyocardial injection of autologous mononuclear bone marrow cells during coronary artery bypass graft (CABG) could improve global and regional left ventricular ejection fraction (LVEF) at 4-month follow-up. Methods and Results— Twenty patients (age 64.8±8.7; 17 male, 3 female) with a postinfarction nonviable scar, as assessed by thallium (Tl) scintigraphy and cardiac magnetic resonance imaging (MRI), scheduled for elective CABG, were included. They were randomized to a control group (n =10, CABG only) or a BMC group (CABG and injection of 60.106±31.106 BMC). Primary end points were global LVEF change and wall thickening changes in the infarct area from baseline to 4-month follow-up, as measured by MRI. Changes in metabolic activity were measured by Tl scintigraphy and expressed as a score with a range from 0 to 4, corresponding to percent of maximal myocardial Tl uptake (4 indicates <50%, nonviable scar; 3, 50% to 60%; 2, 60% to 70%; 1, 70% to 80%; 0>80%). Global LVEF at baseline was 39.5±5.5% in controls and 42.9±10.3% in the BMC group (P=0.38). At 4 months, LVEF had increased to 43.1±10.9% in the control group and to 48.9±9.5% in the BMC group (P=0.23). Systolic thickening had improved from −0.6±1.3 mm at baseline to 1.8±2.6 mm at 4 months in the cell-implanted scars, whereas nontreated scars remained largely akinetic (−0.5±2.0 mm at baseline compared with 0.4±1.7 mm at 4 months, P=0.007 control versus BMC-treated group at 4 months). Defect score decreased from 4 to 3.3±0.9 in the BMC group and to 3.7±0.4 in the control group (P=0.18). Conclusions— At 4 months, there was no significant difference in global LVEF between both groups, but a recovery of regional contractile function in previously nonviable scar was observed in the BMC group.

Natural Naive CD4+CD25+CD127low Regulatory T Cell (Treg) Development and Function Are Disturbed in Multiple Sclerosis Patients: Recovery of Memory Treg Homeostasis during Disease Progression

Patients with relapsing-remitting multiple sclerosis (RR-MS) show a suboptimal CD4+CD25+ regulatory T cell (Treg) function, whereas no Treg alterations are observed in secondary progressive MS (SP-MS) patients. To clarify the difference in Treg activity between early and chronic disease stages in MS, we analyzed the functional capacity and homeostatic parameters of naive CD4+CD25+CD127lowCD45RA+ Tregs (nTregs) and their memory counterparts CD4+CD25+CD127lowCD45RO+ Tregs (mTregs) in untreated MS patients and healthy controls. Interestingly, whereas the suppressive capacity of FACS-sorted nTregs was impaired in both early and chronic MS patients, only the latter group showed a restored mTreg function. Consistent with this observation, chronic MS patients had increased numbers of mTregs as compared with age-matched early MS patients, whereas nTreg frequencies did not differ significantly. TCR excision circle numbers were reduced in nTregs of early MS patients, suggestive of a diminished nTreg thymic output. Moreover, a decreased number of CD31+ mTregs were observed in early vs chronic MS patients, indicating that inflammatory processes drive the homeostatic turnover of mTregs during the early disease stage. Additionally, early MS patients showed a more restricted nTreg and mTreg TCR BV gene profile as compared with healthy controls and chronic MS patients. Finally, analysis of IFN-β and glatiramer acetate-treated MS patients showed that these immunomodulatory drugs modify nTreg homeostasis. Taken together, this study provides strong evidence for a disturbed thymic nTreg development and function in MS patients. Moreover, memory Treg but not naive Treg homeostasis recovers during disease progression.

Secondary progressive in contrast to relapsing-remitting multiple sclerosis patients show a normal CD4+CD25+ regulatory T-cell function and FOXP3 expression

Accumulating evidence indicates an immunosuppressive role for CD4+CD25+ regulatory T cells (Tregs) in autoimmune diseases. Although an impaired Treg function in patients with relapsing‐remitting multiple sclerosis (RR‐MS) has been reported recently, no information is available so far about Treg function in the progressive stage of the disease. In the present study, the phenotypic and functional characteristics of CD4+CD25+ T cells isolated from the peripheral blood of patients with RR‐MS and secondary progressive multiple sclerosis (SP‐MS) were investigated. No significant quantitative or phenotypic abnormalities in CD4+CD25+ T cells from RR‐ and SP‐MS patients were detected. However, whereas a reduced suppressor function of CD4+CD25+ T cells toward proliferation and interferon‐γ production of CD4+CD25– responder T cells was found in RR‐MS patients, SP‐MS patients showed a normal Treg function. The suppressive capacity of MS‐derived CD4+CD25+ T cells was correlated with disease duration but not with age, indicating that Treg function is more affected in the early phase of the disease process. Consistently with the suppressive capacity, CD4+CD25+ T cells from SP‐MS patients showed normal levels of FOXP3 mRNA in contrast to RR‐MS patients that had a reduced FOXP3 expression. These data are the first to demonstrate differences in function and FOXP3 expression of CD4+CD25+ T cells from patients with RR‐ and SP‐MS.

Bone marrow-derived mesenchymal stem cells promote colorectal cancer progression through paracrine neuregulin 1/HER3 signalling

Objective Bone marrow-derived mesenchymal stem cells (BM-MSC) migrate to primary tumours and drive tumour progression. This study aimed to identify the molecular mechanisms associated with these heterotypic cellular interactions and analyse their relevance in colorectal cancer (CRC). Design Paracrine interactions of BM-MSC with CRC cells were studied using collagen invasion assays, cell counts, flow cytometric cell-cycle analysis and tumour xenograft models. The role of neuregulin 1 (NRG1) and the human epidermal growth factor receptor (HER) family pathways were investigated using tyrosine kinase assays, mass spectrometry, pharmacological inhibition, antibody-mediated neutralisation and RNA interference. Transmembrane neuregulin 1 (tNRG1), HER2 and HER3 expression was analysed in primary CRC (n=54), adjacent normal colorectal tissues (n=4), liver metastases (n=3) and adjacent normal liver tissues (n=3) by immunohistochemistry. Results BM-MSC stimulate invasion, survival and tumorigenesis of CRC through the release of soluble NRG1, activating the HER2/HER3-dependent PI3K/AKT signalling cascade in CRC cells. Similarly, tumour-associated mesenchymal cells (T-MC) in CRC demonstrate high tNRG1 expression, which is significantly associated with advanced Union for International Cancer Control stage (p=0.005) and invasion depth (p=0.04) and decreased 5-year progression-free survival (p=0.01). HER2 and HER3 show membrane localisation in cancer cells of CRC tissue. Conclusion Paracrine NRG1/HER3 signals initiated by BM-MSC and T-MC promote CRC cell progression, and high tNRG1 expression is associated with poor prognosis in CRC.

Haplotype 4 of the multiple sclerosis-associated interleukin-7 receptor alpha gene influences the frequency of recent thymic emigrants

The receptor for the homeostatic T cell cytokine interleukin-7 (IL-7Rα) has recently shown genetic association to multiple sclerosis (MS). To investigate the functional contribution of IL-7Rα polymorphisms to the pathogenesis of MS, we correlated the IL-7Rα haplotypes with different T cell parameters in a group of MS patients and healthy controls. We show that carriers of one of the four IL-7Rα haplotypes (Hap4) show a higher expression of IL-7Rα (CD127) on their CD4+ T cells, compared with noncarriers (P=0.04). Moreover, Hap4 carriers possess higher frequencies of recent thymic emigrants (RTEs, CD31+) in both the regulatory T cell (Treg; P=0.007) and conventional T cell (Tconv) population (P=0.0001). This effect is most pronounced within the MS population (Treg, P=0.0077; Tconv, P=0.0007), whereas in healthy controls significance was only reached for Tconv (P=0.043; Treg, P=0.11). Because previous studies showed a decreased RTE–Treg frequency in MS patients compared to healthy subjects, we here conclude that this decrease is localized within the MS population of non-Hap4 carriers. In conclusion, our findings suggest that IL-7Rα polymorphisms can influence T cell development and homeostasis, and thereby contribute to the altered immune regulation associated with disease development in patients with MS.

The cardiac atrial appendage stem cell: a new and promising candidate for myocardial repair

AIMS Considerable shortcomings in the treatment of myocardial infarction (MI) still exist and therefore mortality remains high. Cardiac stem cell (CSC) therapy is a promising approach for myocardial repair. However, identification and isolation of candidate CSCs is mainly based on the presence or absence of certain cell surface markers, which suffers from some drawbacks. In order to find a more specific and reliable identification and isolation method, we investigated whether CSCs can be isolated based on the high expression of aldehyde dehydrogenase (ALDH). METHODS AND RESULTS An ALDH(+) stem cell population, the cardiac atrial appendage stem cells (CASCs), was isolated from human atrial appendages. CASCs possess a unique phenotype that is clearly different from c-kit(+) CSCs but that seems more related to the recently described cardiac colony-forming-unit fibroblasts. Based on immunophenotype and in vitro differentiation studies, we suggest that CASCs are an intrinsic stem cell population and are not mobilized from bone marrow or peripheral blood. Indeed, they possess a clonogenicity of 16% and express pluripotency-associated genes. Furthermore, compared with cardiosphere-derived cells, CASCs possess an enhanced cardiac differentiation capacity. Indeed, differentiated cells express the most important cardiac-specific genes, produce troponin T proteins, and have an electrophysiological behaviour similar to that of adult cardiomyocytes (CMs). Transplanting CASCs in the minipig MI model resulted in extensive cardiomyogenic differentiation without teratoma formation. CONCLUSION We have identified a new human CSC population able to differentiate into functional CMs. This opens interesting perspectives for cell therapy in patients with ischaemic heart disease.

Memory CD4+CD127high T cells from patients with multiple sclerosis produce IL-17 in response to myelin antigens

Myelin-reactive T helper-17 cells are implicated in the pathogenesis of multiple sclerosis (MS). Here, we analyzed the reactivity of peripheral naive and memory conventional CD4(+)CD127(high) T cells (Tconv) of MS patients and healthy controls (HC) towards myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG) and tetanus toxoid (TT). Proliferative responses of Tconv cells towards MBP, MOG and TT were not significantly different between MS patients and HC. However, MBP and MOG but not TT reactive memory Tconv cells from MS patients, in contrast to HC, produced IL-17. These results suggest that myelin antigen reactive Th-17 cells are enriched in MS patients.

Mesenchymal stem cell secreted platelet derived growth factor exerts a pro-migratory effect on resident Cardiac Atrial appendage Stem Cells

Mesenchymal stem cells (MSCs) modulate cardiac healing after myocardial injury through the release of paracrine factors, but the exact mechanisms are still unknown. One possible mechanism is through mobilization of endogenous cardiac stem cells (CSCs). This study aimed to test the pro-migratory effect of MSC conditioned medium (MSC-CM) on endogenous CSCs from human cardiac tissue. By using a three-dimensional collagen assay, we found that MSC-CM improved migration of cells from human cardiac tissue. Cell counts, perimeter and area measurements were utilized to quantify migration effects. To examine whether resident stem cells were among the migrating cells, specific stem cell properties were investigated. The migrating cells displayed strong similarities with resident Cardiac Atrial appendage Stem Cells (CASCs), including a clonogenic potential of ~21.5% and expression of pluripotency associated genes like Oct-4, Nanog, c-Myc and Klf-4. Similar to CASCs, migrating cells demonstrated high aldehyde dehydrogenase activity and were able to differentiate towards cardiomyocytes. Receptor tyrosine kinase analysis and collagen assays performed with recombinant platelet derived growth factor (PDGF)-AA and Imatinib Mesylate, a PDGF receptor inhibitor, suggested a role for the PDGF-AA/PDGF receptor α axis in enhancing the migration process of CASCs. In conclusion, our findings demonstrate that factors present in MSC-CM improve migration of resident stem cells from human cardiac tissue. These data open doors towards future therapies in which MSC secreted factors, like PDGF-AA, can be utilized to enhance the recruitment of CASCs towards the site of myocardial injury.

Clinical benefits of the addition of lower extremity low-intensity resistance muscle training to early aerobic endurance training intervention in patients with coronary artery disease: a randomized controlled trial.

OBJECTIVE Muscle resistance training is often combined with aerobic endurance training during rehabilitation of patients with coronary artery disease. However, the clinical effects of additional lower-extremity low-intensity muscle resistance training during early rehabilitation (within the first month after coronary revascularization) in patients with coronary artery disease remain unclear. DESIGN Prospective randomized controlled trial. SUBJECTS Sixty patients with coronary artery disease. METHODS Subjects were randomly assigned to early aerobic endurance training (n = 30) or combined aerobic endurance and resistance muscle training (n = 30). Subjects performed 18 (standard deviation 2) exercise sessions (at 65% VO(2peak), for 40 mins/session). In resistance muscle training, additional low-intensity (12-20 repetition maximum) resistance muscle exercises were performed. The following parameters were evaluated: exercise capacity, body composition, blood lipid profile, glycaemic control, blood endothelial progenitor cell and cytokine content, and muscle performance. RESULTS A total of 47 patients with coronary artery disease completed the intervention. Total body lean tissue mass tended to increase with greater magnitude (p = 0.07), and blood high-density lipid cholesterol content increased with significantly greater magnitude in resistance muscle training (p < 0.05), compared with aerobic endurance training. Maximal exercise capacity, ventilatory threshold, and muscle performance increased, and steady-state exercise respiratory exchange ratio, and adipose tissue mass reduced significantly (p < 0.05), without differences between groups (p < 0.05). CONCLUSION In early aerobic endurance training intervention in patients with coronary artery disease, additional low-intensity resistance muscle training contributes to a greater increase in blood high-density lipid cholesterol content, and tends to affect lean tissue mass.