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Increased CXCR4 expression and short telomeres in bone marrow mesenchymal stem cells of patients with idiopathic pulmonary fibrosis Foteini Economidou , K aterina M. Antoniou, G iannoula Soufla, A thanasia Proklou, R ena Lymbouridou, H elen Papadaki and Nikolaos M. Siafakas Departments of Thoracic Medicine, Virology and Haematology, Medical School, University of Crete, Heraklion, Greece
Idiopathic Pulmonary fibrosis (IPF) is a devastating condition that leads to progressive lung destruction and scarring.
The mean survival time following diagnosis is less than 5 years .
No effective treatment
The source of fibroblasts involved in the pathogenesis of fibrotic lung disorders is unknown.
Recent evidence indicates that a significant proportion of mesenchymal cells (MSCs) involved in this repair/remodeling process may be derived from extrapulmonary sources, such as the peripheral blood (fibrocytes) and the bone marrow (progenitor cells).
It has been also suggested that the recruitment of MSCs to the lung is mediated via the interaction of the biological axis CXCL12/CXCR4.
This hypothesis is supported further by experimental evidence that antibody neutralization of CXCR12 reduces recruitment of fibrocytes and pulmonary fibrosis.
In contrast, other studies suggest a protective effect of the bone marrow-derived cells.
From Dunsmore S and Shapiro S, JCI 2004
Strieter RM, et al. JCI 2007
Aim of the study
This study investigates:
the reserves and function, the molecular and proteomic profile of BM MSCs and
the expression of the biological axis CXCL12/CXCR4 in patients with Idiopathic Pulmonary Fibrosis (IPF) in comparison with healthy controls .
to probe the possible involvement of MSCs in the pathogenesis of IPF
Table 1: Demographic and spirometric characteristics of IPF patients Values are expressed as mean + SD, and age as median (range). * Statistically significance difference between IPF patients and healthy controls (p<0.05). Abbreviations: FVC, Forced Vital Capacity; TLC, Total Lung Capacity; TL CO Diffusing Capacity for Carbon Monoxide; P α O 2 , Arterial Partial Pressure of Oxygen 80.3 + 10.0 - P α O 2, ( mmHg ) 60.3 + 17.8* 96 + 6 TL CO , ( % pred ) 67.4 + 14.2* 101 + 19 TLC, ( % pred ) 77.3 + 13.0* 103 + 14 FVC, ( % pred ) 8/10 6/ 4 Smokers/non smokers 6 5 (40-75) 5 9 (32- 65) Age, median (yr) 7/3 5/5 Sex: Male/Female 10 10 Number IPF patients Control subjects Characteristics
MSC characterization was based on morphology, immunophenotypic profile (CD34-, CD45-, CD14-, CD90+, CD105+, CD73+, CD146+) and differentiation potential towards three lineages (adipocytes/chondrocytes/osteocytes).
Kastrinaki MC, et al. Ann Rheum Dis 2007
The frequency of MSCs in the BM mononuclear cell fraction was evaluated by using a limiting dilution assay.
We have also assessed the molecular and proteomic characteristics in terms of inflammatory cytokine gene and protein expression of BM MSCs
(VEGF, TGF- β1, FGF-b and SDF/ CXCR4).
1. MSC culture and identification
Immunophenotypic characteristics of MSCs.
Trypsinized MSCs from passage-2 (P2) were immunophenotypically characterised by flow cytometry
Differentiation potential of MSCs at P2
Telomerase activity and telomere length
2. Real-time PCR
3. ELISA for protein evaluation
by Papadaki HA
Antoniou KM, Papadaki HA, Soufla G, et al. ERS 2008
Antoniou KM, Papadaki HA, Soufla G, et al. ERS 2008
MSCs IPF patients (n=10) and age-/sex-matched healthy individuals (n=10) were similar in frequency, differentiation potential, immunophenotypic characteristics.
A significant increase in the mRNA expression has been detected in both SDF-1 –TR1 (mean + SD, 1502 + 4180 versus 36 + 28, p =0.002) and CXCR4 (median, 34325 versus 1.54, p =0.002) in IPF patients.
No statistical difference was found in TGF- β1, FGF-b and VEGF mRNA expression levels between patients and controls.
1. Either the increased expression of CXCR4 occurred as a result of lung injury or
2. it preceded lung injury
We furthermore investigated telomere length in BM-MSCs and telomerase expression in lung tissue of patients with IPF
A specialized ribonucleoprotein-containing enzyme
synthesizes telomere DNA to prevent degeneration of chromosomal ends in actively dividing cells.
Telomerase adds telomere repeats to ends of chromosomes
Two components: hTERT, hTR
Telomerase activity is clearly required for cancer cell propagation
Its role in the injured lung is unknown
Telomeres and IPF
Telomeres are DNA-protein structures that protect chromosome ends.
Short telomeres activate a DNA damage response that leads to cell death or permanent cell cycle arrest.
Telomere length predicts the onset of various diseases.
Telomere length in familial IPF
Specific mutations identified in a few family cases
Early onset of the disease was related to specific telomerase mutations
Armanios et al NEJM 2007
Tsakiri et al PNAS 2007
25% of sporadic cases and 37% of familial cases of pulmonary fibrosis had
telomere lengths <10th percentile
This cannot be explained by coding mutations in telomerase.
Telomere shortening of circulating leukocytes may be a marker for an
increased predisposition toward the development of this age-associated disease.
Cronkhite JT et al. AJRCCM 2008
Telomere length as determined by the quantitative PCR assay for normal controls (green triangles) and IPF samples (blue spots) plotted against age.
Antoniou KM, Papadaki HA, Soufla G, Siafakas NM. AJRCCM 2009 (letter)
Telomerase activity in lung tissue Antoniou KM, et al. AJRCCM 2009
The mobilisation and the reduction of
telomerase length in BM-MSCs may suggest a
pathogenetic role of those cells in IPF.
Dept of Thoracic Medicine Head: Professor Nikolaos Siafakas Interstitial Lung Disease Group Katerina Antoniou, Lecturer Foteini Economidou, MD, PhD Giorgos Margaritopoulos, MD Athanasia Proklou, MD Giannoula Soufla, PhD Rena Lymbouridou, PhD student Konstantinos Karagiannis, PhD student Ismini Lasithiotaki Collaborators: Dept of Haematology Prof Helen Papadaki Christina Kastrinaki, PhD Helen Koutala Athina Damianaki Dept of Clinical Virology Prof DA Spandidos G. Sourvinos, As. Prof