Differential changes in expression of inflammatory mRNA and protein after oleic acid-induced acute lung injury.

Background: Acute Respiratory Distress syndrome (ARDS) is a clinical syndrome of noncardiac pulmonary edema and inflammation leading to acute respiratory failure. We used the oleic acid infusion pig model of ARDS resembling human disease to explore cytokine changes in white blood cells (WBC) and plasma proteins, comparing baseline to ARDS values. Methods: Nineteen juvenile female swine were included in the study. ARDS defined by a PaO2/FiO2 ratio < 300 was induced by continuous oleic acid infusion. Arterial blood was drawn before and during oleic acid infusion, and when ARDS was established. Cytokine expression in WBC was analyzed by RT-qPCR and plasma protein expression by ELISA. Results: The median concentration of IFN-γ mRNA was estimated to be 59% (p = 0.006) and of IL-6 to be 44.4% (p = 0.003) of the baseline amount. No significant changes were detected for TNF-α, IL-17, and IL-10 mRNA expression. In contrast, the concentrations of plasma IFN-γ and IL-6 were significantly higher (p = 0.004 and p = 0.048 resp.), and TNF-α was significantly lower (p = 0.006) at ARDS compared to baseline. Conclusions: The change of proinflammatory cytokines IFN-γ and IL-6 expression is different comparing mRNA and plasma proteins at oleic acid-induced ARDS compared to baseline. The migration of cells to the lung may be the cause for this discrepancy.

NFATc3 regulation of collagen V expression contributes to cellular immunity to collagen type V and hypoxic pulmonary hypertension.

Chronic hypoxia (CH)-induced pulmonary hypertension (PH) results, in part, from T helper-17 (TH17) cell-mediated perivascular inflammation. However, the antigen(s) involved is unknown. Cellular immunity to collagen type V (col V) develops after ischemia-reperfusion injury during lung transplant and is mediated by naturally occurring (n)TH17 cells. Col5a1 gene codifies for the α1-helix of col V, which is normally hidden from the immune system within type I collagen in the extracellular matrix. COL5A1 promoter analysis revealed nuclear factor of activated T cells, cytoplasmic 3 (NFATc3) binding sites. Therefore, we hypothesized that smooth muscle NFATc3 upregulates col V expression, leading to nTH17 cell-mediated autoimmunity to col V in response to CH, representing an upstream mechanism in PH development. To test our hypothesis, we measured indexes of PH in inducible smooth muscle cell (SMC)-specific NFATc3 knockout (KO) mice exposed to either CH (380 mmHg) or normoxia and compared them with wild-type (WT) mice. KO mice did not develop PH. In addition, COL5A1 was one of the 1,792 genes differentially affected by both CH and SMC NFATc3 in isolated intrapulmonary arteries, which was confirmed by RT-PCR and immunostaining. Cellular immunity to col V was determined using a trans vivo delayed-type hypersensitivity assay (Tv-DTH). Tv-DTH response was evident only when splenocytes were used from control mice exposed to CH but not from KO mice, and mediated by nTH17 cells. Our results suggest that SMC NFATc3 is important for CH-induced PH in adult mice, in part, by regulating the expression of the lung self-antigen COL5A1 protein contributing to col V-reactive nTH17-mediated inflammation and hypertension.

Bimodal right ventricular dysfunction after postnatal hyperoxia exposure: implications for the preterm heart.

Rats exposed to postnatal hyperoxia develop right ventricular (RV) dysfunction, mild pulmonary hypertension, and dysregulated cardiac mitochondrial biogenesis when aged to one year, with the degree of cardiac dysfunction and pulmonary hypertension similar to that previously described in young adults born preterm. Here, we sought to understand the impact of postnatal hyperoxia exposure on RV hemodynamic and mitochondrial function across the life span. In Methods, pups from timed-pregnant Sprague-Dawley rats were randomized to normoxia or hyperoxia [fraction of inspired oxygen (FIO2), 0.85] exposure for the first 14 days of life, a commonly used model of chronic lung disease of prematurity. RV hemodynamic and mitochondrial function were assessed by invasive measurement of RV pressure-volume loops and by high-resolution respirometry at postnatal day 21 (P21), P90, and P365. In Results, at P21, hyperoxia-exposed rats demonstrated severe pulmonary hypertension and RV dysfunction, accompanied by depressed mitochondrial oxidative capacity. However, significant upregulation of mitochondrial biogenesis at P21 as well as improved afterload led to complete RV hemodynamic and mitochondrial recovery at P90. Mitochondrial DNA mutations were significantly higher by P90 and associated with significant late RV mitochondrial and hemodynamic dysfunction at P365. In conclusion, there appears to be a "honeymoon period" where cardiac hemodynamic and mitochondrial function normalizes following postnatal hyperoxia exposure, only to decline again with ongoing aging. This finding may have significant implications if a long-term pulmonary vascular screening program were to be developed for children or adults with a history of severe prematurity. Further investigation into the mechanisms of recovery are warranted.NEW & NOTEWORTHY Premature birth is associated with increased risk for cardiac dysfunction and failure throughout life. Here, we identify bimodal right ventricular dysfunction after postnatal hyperoxia exposure. Mitochondrial biogenesis serves as an early adaptive feature promoting recovery of cardiac hemodynamic and mitochondrial function. However, the accumulation of mitochondrial DNA mutations results in late mitochondrial and right ventricular dysfunction. This bimodal right ventricular dysfunction may have important implications for the development of screening programs in the preterm population.

Intraperitoneal injection of MSC-derived exosomes prevent experimental bronchopulmonary dysplasia.

Mesenchymal stromal cell (MSC) derived exosomes mediate tissue protection and regeneration in many injuries and diseases by modulating cell protein production, protecting from apoptosis, inhibiting inflammation, and increasing angiogenesis. In the present study, daily intraperitoneal injection of MSC-derived exosomes protected alveolarization and angiogenesis in a newborn rat model of bronchopulmonary dysplasia (BPD) induced by 14 days of neonatal hyperoxia exposure (85% O2). Exosome treatment during hyperoxia prevented disruption of alveolar growth, increased small blood vessel number, and inhibited right heart hypertrophy at P14, P21, and P56. In vitro, exosomes significantly increased tube-like network formation by HUVEC, in part through a VEGF mediated mechanism. In summary, daily intraperitoneal injection of exosomes increased blood vessel number and size in the lung through pro-angiogenic mechanisms. MSC-derived exosomes therefore have both anti-inflammatory and pro-angiogenic mechanism to protect the lung from hyperoxia induced lung and heart disease associated with BPD.

Postnatal Hyperoxia Exposure Durably Impairs Right Ventricular Function and Mitochondrial Biogenesis.

Prematurity complicates 12% of births, and young adults with a history of prematurity are at risk to develop right ventricular (RV) hypertrophy and impairment. The long-term risk for pulmonary vascular disease, as well as mechanisms of RV dysfunction and ventricular-vascular uncoupling after prematurity, remain poorly defined. Using an established model of prematurity-related lung disease, pups from timed-pregnant Sprague Dawley rats were randomized to normoxia or hyperoxia (fraction of inspired oxygen, 0.85) exposure for the first 14 days of life. After aging to 1 year in standard conditions, rats underwent hemodynamic assessment followed by tissue harvest for biochemical and histological evaluation. Aged hyperoxia-exposed rats developed significantly greater RV hypertrophy, associated with a 40% increase in RV systolic pressures. Although cardiac index was similar, hyperoxia-exposed rats demonstrated a reduced RV ejection fraction and significant RV-pulmonary vascular uncoupling. Hyperoxia-exposed RV cardiomyocytes demonstrated evidence of mitochondrial dysregulation and mitochondrial DNA damage, suggesting potential mitochondrial dysfunction as a cause of RV dysfunction. Aged rats exposed to postnatal hyperoxia recapitulate many features of young adults born prematurely, including increased RV hypertrophy and decreased RV ejection fraction. Our data suggest that postnatal hyperoxia exposure results in mitochondrial dysregulation that persists into adulthood with eventual RV dysfunction. Further evaluation of long-term mitochondrial function is warranted in both animal models of premature lung disease and in human adults who were born preterm.

Cardiopulmonary and histological characterization of an acute rat lung injury model demonstrating safety of mesenchymal stromal cell infusion.

BACKGROUND AIMS: In the field of cellular therapy, potential cell entrapment in the lungs following intravenous administration in a compromised or injured pulmonary system is an important concern that requires further investigation. We developed a rat model of inflammatory and fibrotic lung disease to mimic the human clinical condition of obliterative bronchiolitis (OB) and evaluate the safety of intravenous infusion of mesenchymal stromal cells (MSCs). This model was used to obtain appropriate safety information and functional characterization to support the translation of an ex vivo-generated cellular product into human clinical trials. To overcome spontaneous recovery and size limitations associated with current animal models, we used a novel multiple dose bleomycin strategy to induce lasting lung injury in rats. METHODS: Intratracheal instillation of bleomycin was administered to rats on multiple days. MSCs were intravenously infused 7 days apart. Detailed pulmonary function tests including forced expiratory volume, total lung capacity, and invasive hemodynamic measurements were conducted to define the representative disease model and monitor cardiopulmonary hemodynamic consequences of the cell infusion. Post-euthanasia assessments included a thorough evaluation of lung morphology and histopathology. RESULTS: The double dose bleomycin instillation regimen resulted in severe and irreversible lung injury and fibrosis. Cardiopulmonary physiological monitoring reveled that no adverse events could be attributed to the cell infusion process. DISCUSSION: Although our study did not show the infusion of MSCs to result in an improvement in lung function or rescue of damaged tissue this study does confirm the safety of MSC infusion into damaged lungs.

Effects of chronic intermittent hypoxia on allergen-induced airway inflammation in rats.

Obstructive sleep apnea aggravates asthma, but its mechanisms are unknown. Chronic intermittent hypoxia is one hallmark feature of sleep apnea. In this study, we tested the effects of chronic intermittent hypoxia on allergen-induced inflammation in rats. Four groups (n = 9-11/group) of ovalbumin (OVA)-sensitized Brown-Norway rats underwent intermittent hypoxia (10% oxygen, 30 cycles/h, 10 h/d) or normoxia for 30 days concurrent with weekly OVA or vehicle challenges. Lung physiology, differential leukocyte counts from bronchoalveolar lavage, and histology (Picro Sirius Red staining for collagen content) were compared between groups 2 days after the last challenge. Gene expression in bronchoalveolar lavage cells was quantified by quantitative PCR. Compared with normoxia, chronic intermittent hypoxia reduced the FEV0.1/FVC ratio (P = 0.005), peak expiratory flow (P = 0.002), and mean midexpiratory flow (P = 0.004), predominantly in medium and large airways; decreased the baseline eosinophil number (P = 0.01) and amplified the effect of OVA on monocyte number (P = 0.02 for the interaction); in proximal airways, increased (P = 0.008), whereas in distal airways it decreased (P = 0.004), collagen density; induced qualitative emphysematous changes in lung periphery; and increased expression of the M2 macrophage marker YM-1 and augmented OVA-induced expression of plasminogen activator inhibitor-1. Chronic intermittent hypoxia alters immune response to allergen toward a more TH-1-predominant cellular phenotype with collagen deposition and matrix degradation, leading to airflow limitation. These findings highlight the potential of sleep apnea to aggravate airway dysfunction in patients with preexistent asthma.

Indirect cardiac output assessment in a swine pediatric acute respiratory distress syndrome model.

PURPOSE: To investigate the correlation between volume of carbon dioxide elimination (V̇CO2) and end-tidal carbon dioxide (PETCO2) with cardiac output (CO) in a swine pediatric acute respiratory distress syndrome (ARDS) model. METHODS: Respiratory and hemodynamic variables were collected from twenty-six mechanically ventilated juvenile pigs under general anesthesia before and after inducing ARDS, using oleic acid infusion. RESULTS: Prior to ARDS induction, mean (SD) CO, V̇CO2, PETCO2, and dead space to tidal volume ratio (Vd/Vt) were 4.16 (1.10) L/min, 103.69 (18.06) ml/min, 40.72 (3.88) mmHg and 0.25 (0.09) respectively. Partial correlation coefficients between average CO, V̇CO2, and PETCO2 were 0.44 (95% confidence interval: 0.18-0.69) and 0.50 (0.18-0.74), respectively. After ARDS induction, mean CO, V̇CO2, PETCO2, and Vd/Vt were 3.33 (0.97) L/min, 113.71 (22.97) ml/min, 50.17 (9.73) mmHg and 0.40 (0.08). Partial correlations between CO and V̇CO2 was 0.01 (-0.31 to 0.37) and between CO and PETCO2 was 0.35 (-0.002 to 0.65). CONCLUSION: ARDS may limit the utility of volumetric capnography to monitor CO.

Hyperbaric air mobilizes stem cells in humans; a new perspective on the hormetic dose curve.

Introduction: Hyperbaric air (HBA) was first used pharmaceutically in 1662 to treat lung disease. Extensive use in Europe and North America followed throughout the 19th century to treat pulmonary and neurological disorders. HBA reached its zenith in the early 20th century when cyanotic, moribund "Spanish flu pandemic" patients turned normal color and regained consciousness within minutes after HBA treatment. Since that time the 78% Nitrogen fraction in HBA has been completely displaced by 100% oxygen to create the modern pharmaceutical hyperbaric oxygen therapy (HBOT), a powerful treatment that is FDA approved for multiple indications. Current belief purports oxygen as the active element mobilizing stem progenitor cells (SPCs) in HBOT, but hyperbaric air, which increases tensions of both oxygen and nitrogen, has been untested until now. In this study we test HBA for SPC mobilization, cytokine and chemokine expression, and complete blood count. Methods: Ten 34-35-year-old healthy volunteers were exposed to 1.27ATA (4 psig/965 mmHg) room air for 90 min, M-F, for 10 exposures over 2-weeks. Venous blood samples were taken: (1) prior to the first exposure (served as the control for each subject), (2) directly after the first exposure (to measure the acute effect), (3) immediately prior to the ninth exposure (to measure the chronic effect), and (4) 3 days after the completion of tenth/final exposure (to assess durability). SPCs were gated by blinded scientists using Flow Cytometry. Results: SPCs (CD45dim/CD34+/CD133-) were mobilized by nearly two-fold following 9 exposures (p = 0.02) increasing to three-fold 72-h post completion of the final (10th) exposure (p = 0.008) confirming durability. Discussion: This research demonstrates that SPCs are mobilized, and cytokines are modulated by hyperbaric air. HBA likely is a therapeutic treatment. Previously published research using HBA placebos should be re-evaluated to reflect a dose treatment finding rather than finding a placebo effect. Our findings of SPC mobilization by HBA support further investigation into hyperbaric air as a pharmaceutical/therapy.

Effect of intermittent hyperoxia on stem cell mobilization and cytokine expression.

The best known form of oxygen therapy is hyperbaric oxygen (HBO) therapy, which increases both concentration and atmospheric pressure. HBO supports tissue regeneration and is indicated in an increasing number of pathologies. Less known but still showing some promising effects is normobaric oxygen (NBO) therapy, which provides some advantages over HBO including eliminating barotrauma risk, increased ease of administration and a significant cost reduction. However, still little is known about differences and similarities in treatment effects between HBO and NBO. Therefore we tested whether NBO induces a biological response comparable to HBO with a focus on stem progenitor cell mobilization and changes in serum cytokine concentration. We randomly assigned Sprague-Dawley rats into an NBO treatment group (n = 6), and a room air control group (n = 6). The NBO treatment group was exposed to 42% oxygen for 2 hours a day for 10 days. The room air group was concurrently kept at 20.9% oxygen. The frequency and number of stem progenitor cells in peripheral blood were analyzed by flow cytometry. Plasma cytokine expression was analyzed by cytokine array enzyme linked immunosorbent assay. All analyses were performed 24 hours after the final exposure to control for transient post treatment effects. The NBO treatment group showed an increase in circulating CD133+/CD45+ stem progenitor cell frequency and number compared to the room air control group. This rise was largely caused by CD34- stem progenitor cells (CD133+/CD34-/CD45+) without changes in the CD34+ population. The plasma cytokine levels tested were mostly unchanged with the exception of tumor necrosis factor-α which showed a decrease 24 hours after the last NBO exposure. These findings support our hypothesis that NBO induces a biological response similar to HBO, affecting serum stem progenitor cell populations and tumor necrosis factor-α concentration. The study was approved by Institutional Animal Care and Use Committee (IACUC) of the University of Wisconsin, Madison, WI, USA (approval No. M005439) on June 28, 2016.

Chronic intermittent hypoxia worsens bleomycin-induced lung fibrosis in rats.

Obstructive sleep apnea (OSA) has been linked to increased mortality in pulmonary fibrosis. Its key feature, chronic intermittent hypoxia (CIH), can lead to oxidative stress and inflammation, known to lead to fibrotic pathology in other organs. We tested the effects of CIH in an animal model of bleomycin-induced lung fibrosis. Sprague Dawley rats were instilled intratracheally with bleomycin (Blm) or saline (Sal), and exposed to CIH or normal air (Norm) for 9 or 30 days. Pulmonary function was tested and lungs were harvested for histological and molecular analyses. In Blm-treated animals, 30days of CIH compared to Norm increased total lung collagen content (p=0.008) and reduced Quasi-static lung compliance (p=0.04). CIH upregulated lipid peroxidation and increased NF-κB activation, IL-17 mRNA and Col1α1 mRNA expression. Our results indicate that following Blm-induced lung injury, CIH amplifies collagen deposition via oxidative and inflammatory pathways, culminating in stiffer lungs. Thus, OSA may augment fibrosis in patients with interstitial lung disease.

Sex-Specific Skeletal Muscle Fatigability and Decreased Mitochondrial Oxidative Capacity in Adult Rats Exposed to Postnatal Hyperoxia.

Premature birth affects more than 10% of live births, and is characterized by relative hyperoxia exposure in an immature host. Long-term consequences of preterm birth include decreased aerobic capacity, decreased muscular strength and endurance, and increased prevalence of metabolic diseases such as type 2 diabetes mellitus. Postnatal hyperoxia exposure in rodents is a well-established model of chronic lung disease of prematurity, and also recapitulates the pulmonary vascular, cardiovascular, and renal phenotype of premature birth. The objective of this study was to evaluate whether postnatal hyperoxia exposure in rats could recapitulate the skeletal and metabolic phenotype of premature birth, and to characterize the subcellular metabolic changes associated with postnatal hyperoxia exposure, with a secondary aim to evaluate sex differences in this model. Compared to control rats, male rats exposed to 14 days of postnatal hyperoxia then aged to 1 year demonstrated higher skeletal muscle fatigability, lower muscle mitochondrial oxidative capacity, more mitochondrial damage, and higher glycolytic enzyme expression. These differences were not present in female rats with the same postnatal hyperoxia exposure. This study demonstrates detrimental mitochondrial and muscular outcomes in the adult male rat exposed to postnatal hyperoxia. Given that young adults born premature also demonstrate skeletal muscle dysfunction, future studies are merited to determine whether this dysfunction as well as reduced aerobic capacity is due to reduced mitochondrial oxidative capacity and metabolic dysfunction.

Altered Right Ventricular Mechanical Properties Are Afterload Dependent in a Rodent Model of Bronchopulmonary Dysplasia.

Infants born premature are at increased risk for development of bronchopulmonary dysplasia (BPD), pulmonary hypertension (PH), and ultimately right ventricular (RV) dysfunction, which together carry a high risk of neonatal mortality. However, the role alveolar simplification and abnormal pulmonary microvascular development in BPD affects RV contractile properties is unknown. We used a rat model of BPD to examine the effect of hyperoxia-induced PH on RV contractile properties. We measured in vivo RV pressure as well as passive force, maximum Ca2+ activated force, calcium sensitivity of force (pCa50) and rate of force redevelopment (ktr) in RV skinned trabeculae isolated from hearts of 21-and 35-day old rats pre-exposed to 21% oxygen (normoxia) or 85% oxygen (hyperoxia) for 14 days after birth. Systolic and diastolic RV pressure were significantly higher at day 21 in hyperoxia exposed rats compared to normoxia control rats, but normalized by 35 days of age. Passive force, maximum Ca2+ activated force, and calcium sensitivity of force were elevated and cross-bridge cycling kinetics depressed in 21-day old hyperoxic trabeculae, whereas no differences between normoxic and hyperoxic trabeculae were seen at 35 days. Myofibrillar protein analysis revealed that 21-day old hyperoxic trabeculae had increased levels of beta-myosin heavy chain (ß-MHC), atrial myosin light chain 1 (aMLC1; often referred to as essential light chain), and slow skeletal troponin I (ssTnI) compared to age matched normoxic trabeculae. On the other hand, 35-day old normoxic and hyperoxic trabeculae expressed similar level of α- and ß-MHC, ventricular MLC1 and predominantly cTnI. These results suggest that neonatal exposure to hyperoxia increases RV afterload and affect both the steady state and dynamic contractile properties of the RV, likely as a result of hyperoxia-induced expression of ß-MHC, delayed transition of slow skeletal TnI to cardiac TnI, and expression of atrial MLC1. These hyperoxia-induced changes in contractile properties are reversible and accompany the resolution of PH with further developmental age, underscoring the importance of reducing RV afterload to allow for normalization of RV function in both animal models and humans with BPD.

Biodistribution and Clearance of Human Mesenchymal Stem Cells by Quantitative Three-Dimensional Cryo-Imaging After Intravenous Infusion in a Rat Lung Injury Model.

: Cell tracking is a critical component of the safety and efficacy evaluation of therapeutic cell products. To date, cell-tracking modalities have been hampered by poor resolution, low sensitivity, and inability to track cells beyond the shortterm. Three-dimensional (3D) cryo-imaging coregisters fluorescent and bright-field microcopy images and allows for single-cell quantification within a 3D organ volume. We hypothesized that 3D cryo-imaging could be used to measure cell biodistribution and clearance after intravenous infusion in a rat lung injury model compared with normal rats. A bleomycin lung injury model was established in Sprague-Dawley rats (n = 12). Human mesenchymal stem cells (hMSCs) labeled with QTracker655 were infused via jugular vein. After 2, 4, or 8 days, a second dose of hMSCs labeled with QTracker605 was infused, and animals were euthanized after 60, 120, or 240 minutes. Lungs, liver, spleen, heart, kidney, testis, and intestine were cryopreserved, followed by 3D cryo-imaging of each organ. At 60 minutes, 82% ± 9.7% of cells were detected; detection decreased to 60% ± 17% and 66% ± 22% at 120 and 240 minutes, respectively. At day 2, 0.06% of cells were detected, and this level remained constant at days 4 and 8 postinfusion. At 60, 120, and 240 minutes, 99.7% of detected cells were found in the liver, lungs, and spleen, with cells primarily retained in the liver. This is the first study using 3D cryo-imaging to track hMSCs in a rat lung injury model. hMSCs were retained primarily in the liver, with fewer detected in lungs and spleen. SIGNIFICANCE: Effective bench-to-bedside clinical translation of cellular therapies requires careful understanding of cell fate through tracking. Tracking cells is important to measure cell retention so that delivery methods and cell dose can be optimized and so that biodistribution and clearance can be defined to better understand potential off-target toxicity and redosing strategies. This article demonstrates, for the first time, the use of three-dimensional cryo-imaging for single-cell quantitative tracking of intravenous infused clinical-grade mesenchymal stem cells in a clinically relevant model of lung injury. The important information learned in this study will help guide future clinical and translational stem cell therapies for lung injuries.

Cellular basis of tissue regeneration by omentum.

The omentum is a sheet-like tissue attached to the greater curvature of the stomach and contains secondary lymphoid organs called milky spots. The omentum has been used for its healing potential for over 100 years by transposing the omental pedicle to injured organs (omental transposition), but the mechanism by which omentum helps the healing process of damaged tissues is not well understood. Omental transposition promotes expansion of pancreatic islets, hepatocytes, embryonic kidney, and neurons. Omental cells (OCs) can be activated by foreign bodies in vivo. Once activated, they become a rich source for growth factors and express pluripotent stem cell markers. Moreover, OCs become engrafted in injured tissues suggesting that they might function as stem cells.Omentum consists of a variety of phenotypically and functionally distinctive cells. To understand the mechanism of tissue repair support by the omentum in more detail, we analyzed the cell subsets derived from the omentum on immune and inflammatory responses. Our data demonstrate that the omentum contains at least two groups of cells that support tissue repair, immunomodulatory myeloid derived suppressor cells and omnipotent stem cells that are indistinguishable from mesenchymal stem cells. Based on these data, we propose that the omentum is a designated organ for tissue repair and healing in response to foreign invasion and tissue damage.

Synovial fibroblasts and synovial macrophages from patients with rheumatoid arthritis and other inflammatory joint diseases show chromosomal aberrations.

Chromosomal aberrations were investigated in nuclei extracted from synovial tissue and first-passage synovial fibroblasts (P-1 SFB, 98% enrichment) or macrophages (P-1 Mphi) from patients with rheumatoid arthritis (n=10). The findings were compared with those in other rheumatic diseases (osteoarthritis, n=14; reactive arthritis, n=1), as well as with those in chronic obstructive pulmonary disease (n=8). Controls were paired peripheral blood lymphocytes from arthritic patients, synovial tissue or SFB/Mphi from joint trauma/normals (n=9), and peripheral blood monocytes from normal donors (n=10). GTG banding of metaphase chromosomes and interphase fluorescence in situ hybridization with centromere-specific probes were used. Comparable chromosomal aberrations were observed in synovial tissue and P-1 SFB of patients with rheumatoid arthritis, osteoarthritis, and reactive arthritis (polysomy 7 and aneusomies of chromosomes 4, 8, 9, 12, and 18). Notably, aneusomies of chromosomes 4, 6, 7, 8, 9, 11, 12, and/or X were also detected in P-1 synovial Mphi from rheumatoid arthritis (90% of the cases), osteoarthritis (93%), and reactive arthritis (1/1), as well as bronchial Mphi from chronic obstructive pulmonary disease (25%). No aberrations were detected in paired peripheral blood lymphocytes (except for one osteoarthritis case with a karyotype 45,X[10]/46,XX[17]), or in peripheral blood monocytes and synovial tissue of normals/joint trauma. Because Mphi aberrations were common to chronic joint and pulmonary disease, chronic inflammatory stress may induce chromosomal aberrations with potential functional relevance in local mesenchymal cells and infiltrating leukocytes in an organ-independent fashion.