Impact of elexacaftor/tezacaftor/ivacaftor on respiratory colonization in an adult cystic fibrosis clinic.

BACKGROUND: Little research has been completed on the correlation between cystic fibrosis (CF) modulator therapy and its effect on respiratory cultures in CF patients. This study evaluated the effect of elexacaftor/tezacaftor/ivacaftor (ETI) on respiratory colonization with Pseudomonas aeruginosa. METHODS: This single center, IRB approved, retrospective chart review compared patient data two years immediately prior to ETI initiation with patient data two years post-initiation from January 2017-December 2022. Patients were included in the study if they were at least 18 years old with a diagnosis of CF and had at least one month of ETI dispensed, at least one sputum culture obtained, and were currently on ETI. Those who had not been seen since ETI initiation or received a bilateral lung transplant were excluded. The primary outcome was rate of patients with respiratory colonization post-ETI. Colonization was defined as two or more positive P. aeruginosa cultures in a 12-month period. Decolonization was defined as three consecutive negative P. aeruginosa cultures after previous colonization. Key secondary outcomes included average time to discontinuation of mucolytic therapy and relative risk of pulmonary exacerbation. RESULTS: A significant reduction (p<0.001) in colonization with P. aeruginosa was observed with 49 patients in the pre-ETI group compared to 25 in the post-ETI group meeting the definition of colonization (n=79). Average time to discontinuation of mucolytic therapy was 14 months (p=0.002). Relative risk of pulmonary exacerbation was 4.80 (p<0.001). CONCLUSIONS: ETI use resulted in reduced colonization with P. aeruginosa, discontinuation of mucolytic therapy, and decreased frequency of pulmonary exacerbation.

NEOTROPICAL FRESHWATER FISHES: A dataset of occurrence and abundance of freshwater fishes in the Neotropics.

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

Investigating Defects of Esophageal Motility in Lung Transplant Recipients.

Background: Lung transplant patients are at risk of developing chronic lung allograft dysfunction (CLAD) of which bronchitis obliterans syndrome (BOS) is the most common. These patients also are noted to develop gastrointestinal (GI) disease. Gastroesophageal reflux disease (GERD) is implicated in BOS, and diagnosis and treatment of GERD may help to decrease incidence of BOS. Methods: A total of 131 lung transplant recipients with post-transplant evaluation between 2012 and 2019 were studied. Of 60 post-transplant evaluations with at least 6 months of post-transplant follow-up that included impedance testing, high-resolution manometry (HRM), and pH testing, procedures were performed according to recognized standards. Results: Of 60 patients, 56 (93%) were alive at 1-year post-transplant. The patients were found to have high rates of GI motility diseases: 37 patients (62%) had abnormal impedance testing, 50 patients (83%) had abnormal HRM results, 22 patients (37%) had abnormal pH test results. There was associated high rejection rates in patients with abnormal esophageal motility. There were 37 patients that had abnormal impedance test results and of those 25 patients (67%) developed rejection. Fifty patients had abnormal post-transplant HRM studies, 33 (66%) had an acute cellular rejection episode. Twenty-two patients had abnormal pH results, with 14 (63%) having an acute cellular rejection. Conclusions: Patients undergoing lung transplantation were found to have increased incidence of abnormal GI motility studies of the esophagus. These patients were further found to have increased rejection rates and BOS which has been associated with worsened mortality. Developing a formalized pre- and post-transplant motility study process, using evolving technologies for these patients, may provide guidance of at-risk patients for CLAD and early treatment to prevent CLAD.

Current Status of Vascularized Composite Allotransplantation.

The field of vascularized composite allotransplantation (VCA) has moved from a highly experimental procedure to, at least for some patients, one of the best treatment alternatives for catastrophic tissue loss or dysfunction. Although the worldwide experience is still limited, progress has been made in translation to the clinic, and hand transplantation was recently designated standard of care and is now covered in full by the British Health System. This progress is tempered by the long-term challenges of systemic immunosuppression, and the rapidly evolving indications for VCA such as urogenital transplantation. This update will cover the state of and recent changes in the field, and an update of the Louisville VCA program as our initial recipient, the first person to receive a hand transplant in the United States celebrates the 20th anniversary of his transplant. The achievements and complications encountered over the last two decades will be reviewed. In addition, potential directions for research and collaboration as well as practical issues of how third party payers and funding are affecting growth of the field are presented.

The role of B cell immunity in VCA graft rejection and acceptance.

Vascularized composite allotransplantation (VCA) has emerged as the most recent field of transplantation to offer an alternative treatment for those patients that have failed or are not suitable candidates for conventional therapy. Most of the current clinical experience in this field is with recipients of skin containing grafts such as the face, upper extremity and abdominal wall transplants. Like solid organ recipients, VCA recipients require lifelong systematic immunosuppression to maintain their grafts. To date, the most successful immunosuppressant regimens are calcineurin inhibitor based and have been targeted to the control of T cells. While these regimens have resulted in excellent short term graft survival in solid organ transplantation, achieving significant improvements in long term survival has been more challenging. The reasons are multi-factorial, but a role for B cells and humoral immunity has been proposed. Antibody mediated rejection leading to chronic rejection has been cited as the leading cause of renal graft loss. While the number of VCA transplants performed is still small, evidence to date suggests that antibody mediated rejection may occur less frequently than seen in solid organ transplants. Here we will discuss the role of B cell immunity in solid organ transplantation as it pertains and contrasts to the field of VCA and present some examples of possible sequela of B cell immunity in a series of hand transplant recipients.

Immunosuppression maintenance in vascularized composite allotransplantation: what is just right?

PURPOSE OF REVIEW: Over the last two decades advances in vascularized composite allotransplantation have achieved clinically significant milestones. This review provides a synopsis for immunosuppressive maintenance therapy for VCA and discusses the nuances surrounding the determination of the right amount of immunosuppression in vascularized composite allotransplantation. RECENT FINDINGS: Functional results after vascularized composite allotransplantation remain highly encouraging as are the immunologic outcomes, however, challenges persist. Currently, although conventional immunosuppressive protocols have been successful at preventing allograft loss; they have not totally prevented episodes of acute rejection in the skin. Furthermore, vascularized composite allotransplantation carries a significant risk profile attributed to the complications of life-long, high-dose immunosuppression regimens. SUMMARY: Examining conventional treatment protocols can lead to the development of novel immunosuppression concepts that will ultimately assist in favorably tilting the risk-benefit scale for these life-changing transplants.

Colloid-polymer mixtures under slit confinement.

We report a NVT molecular dynamic study of colloid-polymer mixtures under slit confinement. For this purpose, we are employing the Asakura-Oosawa model for studying colloidal particles, polymer coils, and hard walls as the external confining field. The colloid-polymer size ratio, q, is varied in the range 1⩾q⩾0.4 and the confinement distance, H, in 10σc⩾H⩾3σc, σc being the colloidal diameter. Vapor-liquid coexistence properties are assessed, from which phase diagrams are built. The obtained data fulfill the corresponding states law for a constant H when q is varied. The shift of the polymer and colloidal chemical potentials of coexistence follows a linear relationship with (H-σc)-1 for H≳4σc. The confined vapor-liquid interfaces can be fitted with a semicircular line of curvature (H-σc)-1, from which the contact angle can be obtained. We observe complete wetting of the confining walls for reservoir polymer concentrations above and close to the critical value, and partial wetting for reservoir polymer concentrations above and far from it.

Hypoxia downregulates PPARγ via an ERK1/2-NF-κB-Nox4-dependent mechanism in human pulmonary artery smooth muscle cells.

The ligand-activated transcription factor peroxisome proliferator-activated receptor γ (PPARγ) regulates metabolism, cell proliferation, and inflammation. Pulmonary hypertension (PH) is associated with reduced PPARγ expression, and hypoxia exposure regimens that cause PH reduce PPARγ expression. This study examines mechanisms of hypoxia-induced PPARγ downregulation in vitro and in vivo. Hypoxia reduced PPARγ mRNA and protein levels, PPARγ activity, and the expression of PPARγ-regulated genes in human pulmonary artery smooth muscle cells (HPASMCs) exposed to 1% oxygen for 72 h. Similarly, exposure of mice to hypoxia (10% O2) for 3 weeks reduced PPARγ mRNA and protein in mouse lung. Inhibiting ERK1/2 with PD98059 or treatment with siRNA directed against either NF-κB p65 or Nox4 attenuated hypoxic reductions in PPARγ expression and activity. Furthermore, degradation of H2O2 using PEG-catalase prevented hypoxia-induced ERK1/2 phosphorylation and Nox4 expression, suggesting sustained ERK1/2-mediated signaling and Nox4 expression in this response. Mammalian two-hybrid assays demonstrated that PPARγ and p65 bind directly to each other in a mutually repressive fashion. We conclude from these results that hypoxic regimens that promote PH pathogenesis and HPASMC proliferation reduce PPARγ expression and activity through ERK1/2-, p65-, and Nox4-dependent pathways. These findings provide novel insights into mechanisms by which pathophysiological stimuli such as hypoxia cause loss of PPARγ activity and pulmonary vascular cell proliferation, pulmonary vascular remodeling, and PH. These results also indicate that restoration of PPARγ activity with pharmacological ligands may provide a novel therapeutic approach in selected forms of PH.

TGFß1 Controls PPARγ Expression, Transcriptional Potential, and Activity, in Part, through Smad3 Signaling in Murine Lung Fibroblasts.

Transforming growth factor ß1 (TGFß1) promotes fibrosis by, among other mechanisms, activating quiescent fibroblasts into myofibroblasts and increasing the expression of extracellular matrices. Recent work suggests that peroxisome proliferator-activated receptor γ (PPARγ) is a negative regulator of TGFß1-induced fibrotic events. We, however, hypothesized that antifibrotic pathways mediated by PPARγ are influenced by TGFß1, causing an imbalance towards fibrogenesis. Consistent with this, primary murine primary lung fibroblasts responded to TGFß1 with a sustained downregulation of PPARγ transcripts. This effect was dampened in lung fibroblasts deficient in Smad3, a transcription factor that mediates many of the effects of TGFß1. Paradoxically, TGFß1 stimulated the activation of the PPARγ gene promoter and induced the phosphorylation of PPARγ in primary lung fibroblasts. The ability of TGFß1 to modulate the transcriptional activity of PPARγ was then tested in NIH/3T3 fibroblasts containing a PPARγ-responsive luciferase reporter. In these cells, stimulation of TGFß1 signals with a constitutively active TGFß1 receptor transgene blunted PPARγ-dependent reporter expression induced by troglitazone, a PPARγ activator. Overexpression of PPARγ prevented TGFß1 repression of troglitazone-induced PPARγ-dependent gene transcription, whereas coexpression of PPARγ and Smad3 transgenes recapitulated the TGFß1 effects. We conclude that modulation of PPARγ is controlled by TGFß1, in part through Smad3 signals, involving regulation of PPARγ expression and transcriptional potential.

Surgical correction of gastroesophageal reflux in lung transplant patients is associated with decreased effector CD8 cells in lung lavages: a case series.

BACKGROUND: Lung transplantation is associated with a high incidence of gastroesophageal reflux disease (GERD). The presence of GERD is considered a risk factor for the subsequent development of obliterative bronchiolitis (OB), and surgical correction of GERD by gastric fundoplication (GF) may be associated with increased freedom from OB. The mechanisms underlying a protective effect from OB remain elusive. The objective of this study was to analyze the flow cytometric properties of BAL cells in patients who have undergone GF early after transplant. METHODS: In a single-center lung transplant center, eight patients with GERD who were in the first transplant year underwent GF. Prior to and immediately following GF, BAL cells were analyzed by polychromatic flow cytometry. Spirometry was performed before and after GF. RESULTS: GF was associated with a significant reduction in the frequency of BAL CD8 lymphocytes expressing the intracellular effector marker granzyme B, compared with the pre-GF levels. Twenty-six percent of CD8 cells were granzyme Bhi pre-GF compared with 12% of CD8 cells post-GF (range 8%-50% pre-GF, 2%-24% post-GF, P = .01). In contrast, GF was associated with a significant interval increase in the frequency of CD8 cells with an exhausted phenotype (granzyme Blo, CD127lo, PD1hi) from 12% of CD8 cells pre-GF to 24% post-GF (range 1.7%-24% pre-GF and 11%-47% post-GF, P = .05). No significant changes in spirometry were observed during the study interval. CONCLUSIONS: Surgical correction of GF is associated with a decreased frequency of potentially injurious effector CD8 cells in the BAL of lung transplant recipients.

Vitamin D inhibition of pro-fibrotic effects of transforming growth factor beta1 in lung fibroblasts and epithelial cells.

The mechanisms that control fibroproliferation and matrix deposition in lung fibrosis remain unclear. We speculate that vitamin D deficiency may contribute to pulmonary fibrosis since vitamin D deficiency has been implicated in several diseases. First, we confirmed the presence of vitamin D receptors (VDRs) in cultured NIH/3T3 and lung fibroblasts. Fibroblasts transfected with a vitamin D response element-reporter construct and exposed to the active vitamin D metabolite, 1,25(OH)(2)D(3), showed increased promoter activity indicating VDR functionality in these cells. Testing the effects of 1,25(OH)(2)D(3) on fibroblasts treated with transforming growth factor beta1 (TGFbeta1), considered a driver of many fibrotic disorders, we found that 1,25(OH)(2)D(3) inhibited TGFbeta1-induced fibroblast proliferation in a dose-dependent fashion. 1,25(OH)(2)D(3) also inhibited TGFbeta1 stimulation of alpha-smooth muscle actin expression and polymerization and prevented the upregulation of fibronectin and collagen in TGFbeta1-treated fibroblasts. Finally, we examined how 1,25(OH)(2)D(3) affects epithelial-mesenchymal transformation of lung epithelial cells upon exposure to TGFbeta1. We showed that the TGFbeta1-induced upregulation of mesenchymal cell markers and abnormal expression of epithelial cell markers were blunted by 1,25(OH)(2)D(3). These observations suggest that under TGFbeta1 stimulation, 1,25(OH)(2)D(3) inhibits the pro-fibrotic phenotype of lung fibroblasts and epithelial cells.

Dynamics of human regulatory T cells in lung lavages of lung transplant recipients.

BACKGROUND: Despite advances in the field of lung transplantation, the median survival after lung transplant remains below 5 years. Early rejection is a risk factor for the development of chronic rejection. In animal models of transplant tolerance, regulatory T cells (Tregs) can prevent the establishment of rejection. METHODS: This study was designed to explore the dynamics of Tregs focally and systemically in lung transplant recipients. Sequential surveillance bronchoscopy results were available in 51 patients with at least four sequential samples recovered from each patient at defined times posttransplant. In 36 individuals, a complete year of follow-up data for BAL was analyzed. In 33 of these individuals had a complete year of follow-up data for peripheral blood monocyte cell specimens were also analyzed. Lung lavage cells were recovered from each bronchoscopy and corresponding blood draw and subjected to polychromatic flow cytometry. The percentage of CD4 lymphocytes, which expressed the intracellular transcription factor FoxP3 was recorded at each point. At each time point, lung biopsy specimens were scored for rejection. RESULTS: Lung Treg frequency was significantly more variable than blood Treg frequency. Treg frequency in the lung was increased in the aftermath of acute rejection. In contrast, lung Treg frequency declined sequentially in patients demonstrating continued quiescence. Mean BAL Treg level integrated over the first transplant year correlated inversely with the degree of acute cellular rejection. In contrast, blood Treg levels demonstrated no correlation with lung pathology. CONCLUSIONS: Lung Tregs increase in the setting of acute cellular rejection, whereas declining levels of BAL Tregs correlates with immunologic quiescence.

Efficacy of oral ribavirin in lung transplant patients with respiratory syncytial virus lower respiratory tract infection.

BACKGROUND: Respiratory syncytial virus (RSV) can cause severe lower respiratory tract infection (LRI) and is a risk factor for the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation (LTx). Currently, the most widely used therapy for RSV is inhaled ribavirin. However, this therapy is costly and cumbersome. We investigated the utility of using oral ribavirin for the treatment of RSV infection after LTx. METHODS: RSV was identified in nasopharyngeal swabs (NPS) or bronchoalveolar lavage (BAL) using direct fluorescent antibody (DFA) in 5 symptomatic LTx patients diagnosed with LRI. Data were collected from December 2005 and August 2007 and included: age; gender; type of LTx; underlying disease; date of RSV; pulmonary function prior to, during and up to 565 days post-RSV infection; need for mechanical ventilation; concurrent infections; and radiographic features. Patients received oral ribavirin for 10 days with solumedrol (10 to 15 mg/kg/day intravenously) for 3 days, until repeat NPS were negative. RESULTS: Five patients had their RSV-LRI diagnosis made at a median of 300 days post-LTx. Mean forced expiratory volume in 1 second (FEV(1)) fell 21% (p < 0.012) during infection. After treatment, FEV(1) returned to baseline and was maintained at follow-up of 565 days. There were no complications and no deaths with oral therapy. A 10-day course of oral ribavirin cost $700 compared with $14,000 for nebulized ribavirin at 6 g/day. CONCLUSIONS: Treatment of RSV after LTx with oral ribavirin and corticosteroids is well tolerated, effective and less costly than inhaled ribavirin. Further studies are needed to directly compare the long-term efficacy of oral vs nebulized therapy for RSV.

Oxidation of extracellular cysteine/cystine redox state in bleomycin-induced lung fibrosis.

Several lines of evidence indicate that depletion of glutathione (GSH), a critical thiol antioxidant, is associated with the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, GSH synthesis depends on the amino acid cysteine (Cys), and relatively little is known about the regulation of Cys in fibrosis. Cys and its disulfide, cystine (CySS), constitute the most abundant low-molecular weight thiol/disulfide redox couple in the plasma, and the Cys/CySS redox state (E(h) Cys/CySS) is oxidized in association with age and smoking, known risk factors for IPF. Furthermore, oxidized E(h) Cys/CySS in the culture media of lung fibroblasts stimulates proliferation and expression of transitional matrix components. The present study was undertaken to determine whether bleomycin-induced lung fibrosis is associated with a decrease in Cys and/or an oxidation of the Cys/CySS redox state and to determine whether these changes were associated with changes in E(h) GSH/glutathione disulfide (GSSG). We observed distinct effects on plasma GSH and Cys redox systems during the progression of bleomycin-induced lung injury. Plasma E(h) GSH/GSSG was selectively oxidized during the proinflammatory phase, whereas oxidation of E(h) Cys/CySS occurred at the fibrotic phase. In the epithelial lining fluid, oxidation of E(h) Cys/CySS was due to decreased food intake. Thus the data show that decreased precursor availability and enhanced oxidation of Cys each contribute to the oxidation of extracellular Cys/CySS redox state in bleomycin-induced lung fibrosis.

Attenuation of obliterative bronchiolitis by a CXCR4 antagonist in the murine heterotopic tracheal transplant model.

BACKGROUND: Long-term success in lung transplantation is limited by obliterative bronchiolitis (OB), yet the mechanism for this disease is not well understood. Chemokine SDF-1 and its receptor, CXCR4, have been reported to be involved in several fibrogenic processes by recruiting inflammatory and fibroblast progenitor cells into injured tissues. We hypothesized that the SDF-1/CXCR4 axis also plays a role in the pathogenesis of OB. METHODS: Using the mouse heterotopic allogeneic airway transplant model, we transplanted mouse tracheas from BALB/c donors into C57BL/6 recipients. At Day 10 after transplant, we found high expression of SDF-1 in cells in the sub-epithelial layers of the allograft. Approximately 26% of cells infiltrating the allograft were CD45(+)CXCR4(+), as determined by flow cytometry analysis. RESULTS: Treatment of the recipients with a CXCR4 antagonist, TN14003, decreased cell infiltration into the grafts at Day 10 post-implantation. At Day 42, a significant reduction in luminal occlusion was found in the TN14003-treated animals compared with controls (57.40% vs 98.21%, p < 0.01). To demonstrate the relevance of the SDF-1/CXCR4 axis in OB, sections of lung tissue obtained from lung transplant patients with OB were examined for SDF-1 and CXCR4 expression. We found a higher number of CXCR4- and SDF-1-positive cells in samples from patients with OB as compared with normal lungs. CONCLUSIONS: These findings provide new insights into the mechanisms of lung chronic rejection and may lead to new intervention tools for the treatment of OB.

Dapsone-induced hemolytic anemia in lung allograft recipients.

BACKGROUND: Lung transplant (LT) recipients often receive dapsone for Pneumocystis jirovecii pneumonia (PCP) prophylaxis. However, the prevalence of dapsone-induced hematologic toxicity in LT recipients is unknown. We report a high prevalence of hemolytic anemia (HA) associated with dapsone use in LT patients when compared with other patients described in the literature who have been prescribed dapsone prophylaxis. METHODS: We performed a retrospective chart review on all LT recipients who received dapsone prophylaxis between 2004 and 2006. Demographics, ideal body weight (IBW), severity of anemia, transfusion requirements, laboratory evidence of hemolysis, serum creatinine and glucose-6-phosphate deyhdrogenase (G6PD) enzyme levels were collected. RESULTS: Forty-three patients received dapsone. Ten (22.7%) patients had HA, despite normal G6PD levels. The mean drop in hemoglobin from baseline was 2.7 g/dl (95% confidence interval [CI] 1.9 to 3.5, p < 0.0001). Of those patients with HA, 6 had elevated serum creatinine from baseline. The odds ratio for hemolysis was 4.75 for each 1.0-mg/dl increase in creatinine (95% CI 1.07 to 21.03, p = 0.04). Mean IBW for the HA group was 58.4 kg. A dapsone dose of 100 mg/day orally resulted in a mean dose of 1.7 mg/kg. CONCLUSIONS: The prevalence of dapsone-induced HA in LT recipients is 5-fold higher than the reported rate in the population of human immunodeficiency virus (HIV) patients. Individuals with renal failure or low body weight and for whom dose exceeds 1.5 mg/kg may be at increased risk for dapsone-induced HA. Although current CDC guidelines do not recommend adjusting dose by IBW or renal function, we suggest that consideration should be given to these dosing strategies.

Bilateral lung transplant with pulmonary thromboendarterectomy for Eisenmenger's syndrome.

Patients with secondary pulmonary hypertension frequently present for evaluation for lung transplantation. In some of these patients, Eisenmenger's syndrome has developed from chronic left to right intracardiac shunts. A smaller group of these patients will also have associated pulmonary artery aneurysms. There is a paucity of literature discussing this topic, however, and currents reports have suggested the need to replace the abnormal pulmonary artery. This paper discusses a patient in whom Eisenmenger's syndrome developed from an atrial septal defect, and resultant pulmonary artery aneurysms and mural thrombi, who underwent successful bilateral lung transplantation with thromboendarterectomy and atrial septal defect closure.

Activation of Tissue Remodeling Precedes Obliterative Bronchiolitis in Lung Transplant Recipients.

Obliterative bronchiolitis (OB) and Bronchiolitis Obliterans Syndrome (BOS) are frequent complications in the lung transplant recipient, and are the leading cause of mortality after transplantation. The mechanisms responsible for OB remain elusive, but inflammatory and tissue remodeling responses are implicated. We hypothesized that alterations in markers of tissue remodeling in BALF of lung transplant recipients could predict development of OB. To test this, we identified 13 lung transplant recipients who developed both BOS and histologic OB (OB group) at median post-operative day (POD) 485 (range 73-2070). Bronchoalveolar lavage fluid (BALF) was obtained at median POD 387 (range 45-2205), which preceded the onset of OB and BOS by a median of 140 days (range 60-365). As a control, BALF was also obtained from a group of 21 stable recipients without OB (non-OB group) at median POD 335 (range 270-395). BALF was examined for gelatinolytic activity, fibronectin gene transcription, and transforming growth factor-beta1 (TGF-beta1) expression. Gelatin zymography of BALF from the OB group showed increased matrix metalloproteinase-9 (MMP-9) activity over that of the non-OB group (p < 0.005). Similarly, BALF from the OB group induced greater fibronectin expression in fibroblasts compared to the non-OB group (p < 0.03). The induction of fibronectin also correlated with the amount of TGF-beta1 protein in BALF (r = 0.71) from the OB group. We conclude that activation of tissue remodeling precedes the onset of OB, and analysis of gelatinolytic and/or fibronectin-inducing activity in BALF can serve as an early, pre-clinical marker for OB.

Extracellular cysteine/cystine redox potential controls lung fibroblast proliferation and matrix expression through upregulation of transforming growth factor-beta.

Oxidant stress has been implicated in the pathogenesis of chronic lung disorders like idiopathic pulmonary fibrosis. However, mechanisms that link oxidant stress to fibrogenesis remain partially elucidated. Emerging data suggest an important role for the extracellular thiol/disulfide redox environment. The cysteine (Cys)/cystine (CySS) redox couple represents the predominant low-molecular-weight thiol/disulfide pool found in plasma and is sensitive to aging, smoking, and other host factors. We hypothesized that an oxidized extracellular Cys/CySS redox potential (E(h) Cys/CySS) affects lung fibroblasts by inducing intracellular signals that stimulate proliferation and matrix expression. We tested this hypothesis in primary murine lung fibroblasts and found that an oxidized E(h) Cys/CySS (-46 mV) stimulated lung fibroblast proliferation. Furthermore, it stimulated their expression of fibronectin, a matrix glycoprotein highly expressed in fibrotic lung diseases and implicated in lung injury. This stimulatory effect was dependent on protein kinase C activation. Oxidant stress also increased the phosphorylation of cAMP response element binding protein, a transcription factor known for its ability to stimulate fibronectin expression, and increased the expression of mRNAs and proteins coding for the transcription factors nuclear factor (NF)-kappaB and mothers against decapentaplegic homolog 3. Fibroblasts cultured in normal (-80 mV) or reduced (-131 mV) E(h) Cys/CySS showed less induction. Furthermore, fibronectin expression in response to an oxidized E(h) Cys/CySS was associated with expression of transforming growth factor-beta1 (TGF-beta1) and was inhibited by an anti-TGF-beta1 antibody and SB-431542, a TGF-beta1 receptor inhibitor. These studies suggest that extracellular oxidant stress activates redox-sensitive pathways that stimulate lung fibroblast proliferation and matrix expression through upregulation of TGF-beta1.