Martin H. Stradner

An effective approach to prevent immune rejection of human ESC-derived allografts.

Human embryonic stem cells (hESCs) hold great promise for cell therapy as a source of diverse differentiated cell types. One key bottleneck to realizing such potential is allogenic immune rejection of hESC-derived cells by recipients. Here, we optimized humanized mice (Hu-mice) reconstituted with a functional human immune system that mounts a vigorous rejection of hESCs and their derivatives. We established knockin hESCs that constitutively express CTLA4-Ig and PD-L1 before and after differentiation, denoted CP hESCs. We then demonstrated that allogenic CP hESC-derived teratomas, fibroblasts, and cardiomyocytes are immune protected in Hu-mice, while cells derived from parental hESCs are effectively rejected. Expression of both CTLA4-Ig, which disrupts T cell costimulatory pathways, and PD-L1, which activates T cell inhibitory pathway, is required to confer immune protection, as neither was sufficient on their own. These findings are instrumental for developing a strategy to protect hESC-derived cells from allogenic immune responses without requiring systemic immune suppression.

Epigenetic differences in human cartilage between mild and severe OA

The development of osteoarthritis (OA) depends on genetic and environmental factors, which influence the biology of the chondrocyte via epigenetic regulation. Changes within the epigenome might lead the way to discovery of new pathogenetic pathways. We performed a genome‐wide methylation screening to identify potential differences between paired mild and severe osteoarthritic human cartilage. Sixteen female patients suffering from OA underwent total knee joint replacement. Cartilage specimens collected from corresponding macroscopically undamaged and from damaged areas were processed for DNA extraction and histology to evaluate the histological grading of the disease. Paired specimens were analysed for the methylation status of the whole genome using human promoter microarrays (Agilent, Santa Clara, CA). Selected target genes were then validated via methylation‐specific qPCR. One thousand two hundred and fourteen genetic targets were identified differentially methylated between mild and severe OA. One thousand and seventy of these targets were found hypermethylated and 144 hypomethylated. The descriptive analysis of these genes by Gene Ontology (GO), KEGG pathway and protein domain analyses points to pathways of development and differentiation. We identified a list of genes which are differently methylated in mild and severe OA cartilage. Within the pathways of growth and development new therapeutic targets might arise by improving our understanding of pathogenetic mechanisms in OA.

Ultrasound for diagnosis of carpal tunnel syndrome: comparison of different methods to determine median nerve volume and value of power Doppler sonography

Objective To compare ultrasound measurement of median nerve cross-sectional area (CSA) at different anatomical landmarks and to assess the value of power Doppler signals within the median nerve for diagnosis of carpal tunnel syndrome (CTS). Methods A prospective study of 135 consecutive patients with suspected CTS undergoing two visits within 3 months. A final diagnosis of CTS was established by clinical and electrophysiological findings. CSA was sonographically measured at five different levels at forearm and wrist; and CSA wrist to forearm ratios or differences were calculated. Intraneural power Doppler signals were semiquantitatively graded. Diagnostic values of different ultrasound methods were compared by receiver operating characteristic curves using SPSS. Results CTS was diagnosed in 111 (45.5%) wrists; 84 (34.4%) had no CTS and 49 (20.1%) were possible CTS cases. Diagnostic values were comparable for all sonographic methods to determine median nerve swelling, with area under the curves ranging from 0.75 to 0.85. Thresholds of 9.8 and 13.8 mm2 for the largest CSA of the median nerve yielded a sensitivity of 92% and a specificity of 92%. A power Doppler score of 2 or greater had a specificity of 90% for the diagnosis of CTS. Sonographic median nerve volumetry revealed a good reliability with an intraclass correlation coefficient of 0.90 (95% CI 0.79 to 0.95). Conclusions Sonographic assessment of median nerve swelling and vascularity allows for a reliable diagnosis of CTS. Determination of CSA at its maximal shape offers an easily reproducible tool for CTS classification in daily clinical practice.

E and Id Proteins Influence Invariant NKT Cell Sublineage Differentiation and Proliferation

Disease outcome is known to be influenced by defined subsets of invariant NKT (iNKT) cells residing in distinct locations within peripheral tissue. However, the factors governing the development of these unique iNKT sublineages during thymic development are unknown. In this study we explored the mechanism by which E protein transcription factors and their negative regulators, the Id proteins, control the development of iNKT sublineages after positive selection. We found that E proteins directly bound the promyelocytic leukemia zinc finger (PLZF) promoter and were required for expression of this lineage-defining transcription factor and for the maturation and expansion of thymic iNKT cells. Moreover, expression of the negative regulators of E proteins, Id2 and Id3, defined distinct iNKT cell sublineages. Id3 was expressed in PLZFhigh NKT2 cells and loss of Id3 allowed for increased thymic iNKT cell expansion and abundance of the PLZF+ NKT2 sublineage. Id2 was expressed in T-BET+ NKT1 cells, and both Id proteins were required for the formation of this sublineage. Thus, we provide insight into E and Id protein regulation of iNKT cell proliferation and differentiation to specific sublineages during development in the thymus.

Histamine contributes to increased RANKL to osteoprotegerin ratio through altered nuclear receptor 4A activity in human chondrocytes.

OBJECTIVE To elucidate histamine receptor-mediated signaling pathways, transcriptional events, and target gene expression in human cartilage. METHODS Histamine modulation of cartilage destruction was assessed by Safranin O staining and proteoglycan release. H(1) , H(2) , H(3) , and H(4) histamine receptor-dependent regulation of transcription factors (nuclear receptor 4A1 [NR4A1], NR4A2, and NR4A3), RANKL, and osteoprotegerin (OPG) messenger RNA (mRNA) levels were measured in primary and SW-1353 chondrocyte cells using quantitative polymerase chain reaction and selective histamine receptor antagonists. Soluble RANKL and OPG protein levels were determined using enzyme-linked immunosorbent assays. NR4A protein levels and transactivity were evaluated by Western blot analysis, immunocytochemistry, and luciferase reporter assays. Stable depletion of NR4A1-3 was achieved by lentiviral transduction of NR4A short hairpin RNA. RESULTS Primary human chondrocyte cells expressed differential steady-state levels of H(1) -H(4) histamine receptor mRNA. In combination with tumor necrosis factor α, histamine significantly promoted cartilage proteoglycan depletion and release. Histamine modulated the expression of NR4A1-3 orphan receptors in primary and immortalized human chondrocyte cells in a time- and concentration-dependent manner. Histamine selectively signaled through H(1) and H(2) histamine receptors in chondrocytes to modulate RANKL and NR4A2 expression. The temporal effects of histamine on NR4A2 gene transcription were reduced in cells pretreated with inhibitors directed against protein kinase A, MAPK, and NF-κB signaling pathways. Histamine modulated the expression of RANKL with modest effects on OPG levels, leading to increased RANKL:OPG mRNA and protein ratios. Stable knockdown of NR4A1-3 expression resulted in reduced endogenous OPG levels and the loss of histamine-dependent regulation of RANKL expression. CONCLUSION Our findings indicate that histamine, via H(1) and H(2) histamine receptors, contributes to joint disease by enhancing the ratio of RANKL to OPG expression through altered NR4A activity in human chondrocyte cells.

Sphingosine 1-Phosphate Counteracts the Effects of Interleukin-1β in Human Chondrocytes

Objective The lipid mediator sphingosine 1-phosphate (S1P) is found in the synovial fluid of osteoarthritis (OA) patients. S1P protects bovine cartilage by counteracting the effects of interleukin-1β (IL-1β). This study was undertaken to examine the interaction of S1P and IL-1β in human OA chondrocytes. Methods Human cartilage was obtained from patients undergoing total knee joint replacement. Chondrocytes were cultured in monolayer and treated with IL-1β and S1P. Expression of S1P receptor subtypes and genes involved in cartilage degradation was evaluated using real-time polymerase chain reaction, immunohistochemistry, and Western blotting. S1P signaling was evaluated using inhibitors of S1P receptors and small interfering RNA (siRNA) knockdown of the S1P2 receptor. Phosphorylation of MAP kinases and NF-κB in response to IL-1β and S1P was detected by Western blotting. Results S1P2 was identified as the most prevalent S1P receptor subtype in human OA cartilage and chondrocytes in vitro. S1P reduced expression of inducible nitric oxide synthase (iNOS) in IL-1β–treated chondrocytes. Reduction of ADAMTS-4 and matrix metalloproteinase 13 expression by S1P correlated with S1P2 expression. Pharmacologic inhibition of the S1P2 receptor, but not the S1P1 and S1P3 receptors, abrogated the inhibition of iNOS expression. Similar results were observed using siRNA knockdown. S1P signaling inhibited IL-1β–induced phosphorylation of p38 MAPK. Conclusion In human chondrocytes, S1P reduces the induction of catabolic genes in the presence of IL-1β. Activation of the S1P2 receptor counteracts the detrimental phosphorylation of p38 MAPK by IL-1β.

It’s more than dryness and fatigue: The patient perspective on health-related quality of life in Primary Sjögren’s Syndrome - A qualitative study

Objectives In Primary Sjögren’s Syndrome (PSS), there is an apparent lack of data concerning the perspectives of patients, their needs, preferences and difficulties of daily life. This qualitative study was conducted to explore perspectives and needs of patients with PSS that influence health related quality of life (HRQL). Methods We recruited 20 PSS patients fulfilling the American-European consensus classification criteria out of the PSS cohort of the Medical University Graz, Austria. In total, 6 focus group sessions (with three to four patients per group) were performed. A modified meaning condensation procedure was used to analyse the data. Results The interview analysis resulted in 484 meaning units, 254 subconcepts and 86 concepts. The identified concepts were grouped into three dimensions: physical dimension, psychological & emotional challenges and social life & daily living. A dependency between the three categories was identified. The concepts most commonly reported by patients were related to the physical dimension: pain and dryness as well as complaints associated with/provoked by these symptoms. Patients also reported shortness of breath, fatigue und constipation. Conclusions This qualitative study underpins that HRQL in PSS patients is affected by several factors. The problems are not limited to dryness, pain and fatigue while the complaints secondary to these symptoms are important to patients with PSS significantly affecting physical, psychological and social life components of HRQL. A disease-specific patient related outcome measures for clinical practice and trials should be developed considering the different aspects of HRQL in PSS.

Whole body hyperthermia treatment increases interleukin 10 and toll-like receptor 4 expression in patients with ankylosing spondylitis: A pilot study

Abstract Purpose: Exposure to increased environmental temperatures is commonly used as a non-pharmacological treatment modality in ankylosing spondylitis (AS). We aimed to investigate systemic immunological effects of moderate whole body hyperthermia in patients with AS compared to healthy control subjects. Materials and methods: Ten healthy control subjects and six AS patients underwent whole body hyperthermia treatment with 38.7–39 °C body core temperature over 60 min. Numbers of polymorphonuclear leucocytes and lymphocyte subsets, plasma concentrations of several acute phase reactants and cytokines, and gene expression levels of toll-like receptor 4 (TLR-4), interleukin 10 (IL-10) and heat shock protein beta 1 (HSPB1) were determined during and up to 24 h after treatment. Results: TLR-4, IL-10 and HSPB1 gene expression increased significantly up to 3 h post treatment, with an earlier, higher and more pronounced increase of IL-10 in patients with AS. An increase of natural killer cells and CD8+ T lymphocytes was noted during active heating, with a subsequent decrease up to 2 h after treatment. CD4+ T lymphocytes showed a short increase during active treatment in AS patients, while decreasing immediately after start of treatment in control subjects. Neutrophil granulocytes increased significantly up to 3 h after treatment, monocytes and B lymphocytes remained unchanged. Likewise, no significant changes were found concerning systemic cytokine concentrations and acute phase reactants. Conclusions: Our data support the concept of systemic immunological effects of moderate whole body hyperthermia in patients with AS.

Novel Senescent Regulatory T-Cell Subset with Impaired Suppressive Function in Rheumatoid Arthritis

Objective Premature senescence of lymphocytes is a hallmark of inflammatory rheumatic diseases such as rheumatoid arthritis (RA). Early T-cell aging affects conventional T-cells but is presumably not limited to this cell population; rather it might also occur in the regulatory T-cells (Tregs) compartment. In RA, Tregs fail to halt aberrant immune reactions and disease progression. Whether this is associated with early Treg senescence leading to phenotypic and functional changes of this subset is elusive so far. Methods Eighty-four RA patients and 75 healthy controls were prospectively enrolled into the study. Flow cytometry, magnetic-associated cell sorting, and cell culture experiments were performed for phenotypic and functional analyses of Treg subsets. T-cell receptor excision circle (TREC) levels and telomere lengths were determined using RT-PCR. Results In this paper, we describe the novel CD4+FoxP3+CD28− T-cell subset (CD28− Treg-like cells) in RA patients revealing features of both Tregs and senescent T-cells: Treg surface/intracellular markers such as CD25, CTLA-4, and PD-1 as well as FOXP3 were all expressed by CD28− Treg-like cells, and they yielded signs of premature senescence including reduced TREC levels and an accumulation of γH2AX. CD28− Treg-like could be generated in vitro by stimulation of (CD28+) Tregs with TNF-α. CD28− Treg-like cells insufficiently suppressed the proliferation of effector T-cells and yielded a pro-inflammatory cytokine profile. Conclusion In conclusion, we describe a novel T-cell subset with features of Tregs and senescent non-Tregs. These cells may be linked to an aberrant balance between regulatory and effector functions in RA.

Regulation of MMP3 by laminin alpha 4 in human osteoarthritic cartilage.

The degradation of cartilage is characterized by a loss of extracellular matrix (ECM) and the appearance of clusters of hypertrophic chondrocytes (1). The transmembrane proteoglycan syndecan is inv...