Acute inflammatory injury in the lung precipitated by oxidant stress induces fibroblasts to synthesize and release transforming growth factor-alpha

T Regulatory Cell Subsets Do Not Restore for One Year After Acute COVID-19

COVID-19, caused by SARS-CoV-2, triggers a complex immune response, with T regulatory cells (Tregs) playing a crucial role in maintaining immune homeostasis and preventing excessive inflammation. The current study investigates the function of T regulatory cells during COVID-19 infection and the subsequent recovery period, emphasizing their impact on immune regulation and inflammation control. We conducted a comprehensive analysis of Treg subpopulations in peripheral blood samples from COVID-19 patients at different stages: acute infection, early convalescence, and long-term recovery. Flow cytometry was employed to quantify Tregs including "naïve", central memory (CM), effector memory (EM), and terminally differentiated CD45RA+ effector cells (TEMRA). Additionally, the functional state of the Tregs was assessed by the expression of purinergic signaling molecules (CD39, CD73). Cytokine profiles were assessed through multiplex analysis. Our findings indicate a significant decrease in the number of Tregs during the acute phase of COVID-19, which correlates with heightened inflammatory markers and increased disease severity. Specifically, we found a decrease in the relative numbers of "naïve" and an increase in EM Tregs, as well as a decrease in the absolute numbers of "naïve" and CM Tregs. During the early convalescent period, the absolute counts of all Treg populations tended to increase, accompanied by a reduction in pro-inflammatory cytokines. Despite this, one year after recovery, the decreased subpopulations of regulatory T cells had not yet reached the levels observed in healthy donors. Finally, we observed the re-establishment of CD39 expression in all Treg subsets; however, there was no change in CD73 expression among Tregs. Understanding these immunological changes across different T regulatory subsets and adenosine signaling pathways offers important insights into the disease's pathogenesis and provides a broader view of immune system dynamics during recovery.

Magnolia kobus DC leaf ethanol extract alleviated lipopolysaccharide-induced acute lung inflammation by suppressing NF-κB and Nrf2 signaling

Introduction: Magnolia kobus DC has been used as herbal medicine to treat coughs and is known to exert biological effects such as anti-inflammatory, antioxidant, and antibacterial properties. We aimed to define the pharmacological effects of M. kobus leaf ethanol extract (MLEE) on acute lung inflammation and explore the underlying mechanisms of action. Methods: For in vitro investigations, RAW 264.7 cells were pretreated with MLEE (1, 10, and 100 μg/mL) and stimulated with lipopolysaccharide (LPS). For in vivo investigations, BALB/c mice were intratracheally administered with LPS for 24 hours after injection of MLEE (0.3, 3, and 30 mg/kg). Hematoxylin and eosin staining was used for histopathology analysis of lung tissue. The phytochemical constituents of MLEE were analyzed using high-performance liquid chromatography. Results: In RAW 264.7 cells, MLEE reduced the activation of the inflammatory mediators (inducible nitric oxide synthase and cyclooxygenase-2) and the nuclear translocation of nuclear factor (NF)-κB and nuclear factor erythroid-2-related factor 2 (Nrf2). The intraperitoneal injection of MLEE (30 mg/kg) attenuated interstitial edema and immune cell infiltration in LPS-induced acute lung inflammation. MLEE also inhibited the activation of cyclooxygenase-2, NF-κB, and Nrf2 in the lung tissue. Conclusion: Taken together, MLEE exerted an anti-inflammatory effect by inhibiting inflammatory and oxidative mediators on acute lung inflammation suggesting that it might be used as a natural drug for treating acute lung inflammatory diseases.

Quantitative Assessment of Low-Dose Photodynamic Therapy Effects on Diabetic Wound Healing Using Raman Spectroscopy

One of challenges that faces diabetes is the wound healing process. The delayed diabetic wound healing is caused by a complicated molecular mechanism involving numerous physiological variables. Low-dose photodynamic therapy (LDPDT) provides excellent results in rejuvenation and wound healing. In this study, the LDPDT effect on diabetic wounds in mice was studied using two photosensitizers, 5-aminolevulinic acid and methylene blue, and two laser dose expositions of 1 J/cm² and 4 J/cm² by Raman spectroscopy (RS). The latter was used as a noninvasive method, providing specific information about tissue state based on the fundamental vibrational modes of its molecular components. RS allows high spatial resolution acquisition of biochemical and structural information through the generation of point spectra or spectral images. An approach to in vivo quantitative assessment of diabetic wound healing state was developed. This approach is based on an application of the principal component analysis combined with the Mahalanobis metrics to skin Raman spectra, in particular, intensities of the amide I and CH₂ bands.

Shift of lung macrophage composition is associated with COVID-19 disease severity and recovery

Though it has been 2 years since the start of the Coronavirus Disease 19 (COVID-19) pandemic, COVID-19 continues to be a worldwide health crisis. Despite the development of preventive vaccines, very little progress has been made to identify curative therapies to treat COVID-19 and other inflammatory diseases which remain a major unmet need in medicine. Our study sought to identify drivers of disease severity and death to develop tailored immunotherapy strategies to halt disease progression. Here we assembled the Mount Sinai COVID-19 Biobank which was comprised of ~600 hospitalized patients followed longitudinally during the peak of the pandemic. Moderate disease and survival were associated with a stronger antigen (Ag) presentation and effector T cell signature, while severe disease and death were associated with an altered Ag presentation signature, increased numbers of circulating inflammatory, immature myeloid cells, and extrafollicular activated B cells associated with autoantibody formation. Strikingly, we found that in severe COVID-19 patients, lung tissue resident alveolar macrophages (AM) were not only severely depleted, but also had an altered Ag presentation signature, and were replaced by inflammatory monocytes and monocyte-derived macrophages (MoMΦ). Notably, the size of the AM pool correlated with recovery or death, while AM loss and functionality were restored in patients that recovered. These data therefore suggest that local and systemic myeloid cell dysregulation is a driver of COVID-19 severity and that modulation of AM numbers and functionality in the lung may be a viable therapeutic strategy for the treatment of critical lung inflammatory illnesses.

Non-thermal plasma promotes hair growth by improving the inter-follicular macroenvironment

Non-thermal plasma (NTP) is widely used in the disinfection and surface modification of biomaterials. NTP treatment can regenerate and improve skin function; however, its effectiveness on hair follicle (HF) growth and its underlying mechanisms need to be elucidated. Herein, we propose an air-based NTP treatment, which generates exogenous nitric oxide (eNO), as a therapeutic strategy for hair growth. The topical application of air-based NTP generates large amounts of eNO, which can be directly detected using a microelectrode NO sensor, in the dermis of mouse dorsal skin. Additionally, NTP-induced eNO has no cytotoxicity in normal human skin cells and promotes hair growth by increasing capillary tube formation, cellular proliferation, and hair/angiogenesis-related protein expression. Furthermore, NTP treatment promotes hair growth with adipogenesis and activation of CD34⁺CD44⁺ stem cells and improves the inter-follicular macroenvironment via increased perifollicular vascularity in the mouse hair regrowth model. Given the importance of the hair follicle (HF) cycle ratio (growth vs. regression vs. resting) in diagnosing alopecia, NTP treatment upregulates the stem cell activity of the HF to promote the anagen : catagen : telogen ratio, leading to improved hair growth. We confirmed the upregulation of increasing Wnt/β-catenin signaling and activation of perifollicular adipose tissue and angiogenesis in HF regeneration. In conclusion, these results show that the eNO from NTP enhances the cellular activities of human skin cells and endothelial cells in vitro and stem cells in vivo, thereby increasing angiogenesis, adipogenesis, and hair growth in the skin dermis. Furthermore, the results of this study suggest that NTP treatment may be a highly efficient alternative in regenerative medicine for achieving enhanced hair growth.

Non-thermal plasma (NTP) is widely used in the disinfection and surface modification of biomaterials.

Isoliquiritin promote angiogenesis by recruiting macrophages to improve the healing of zebrafish wounds

Licorice is a widely used herbal medicine for the treatment of various diseases in southern Europe and parts of Asia. It has been reported that the isoliquiritin (ISL) from Glycyrrhiza root has the activity of promoting angiogenesis. The purpose of this study was to investigate the effect of ISL on the wound healing activity of zebrafish and its mechanism. 6-month-old zebrafish were injured in the skin (2 mm in diameter) and then treated with ISL. By measuring wound size and by histological examination, we found that ISL improved wound healing. In addition, 4-day-old zebrafish embryos of double transgenic line [Tg(fli-1:EGFP)]/[Tg(mpeg:mCherry)] were suffered from tissue traumas and then treated with ISL. Through fluorescent microscopy, we found that ISL promoted macrophage recruitment and angiogenesis in the wound area. Through qPCR analysis, we found that ISL up-regulated the expression of genes related to inflammation and angiogenesis in zebrafish embryos. These results showed that ISL could promote inflammatory response and angiogenesis, which played key roles in promoting wound healing. Therefore, ISL can be used as a promising candidate to promote wound healing.

Redox dysregulation in the pathogenesis of chronic venous ulceration

In chronic venous ulcers (CVUs), which account for up to 75% of leg ulcers, the inflammatory stage of wound healing fails to down-regulate, preventing progression to proliferation, remodeling and eventual epithelialisation. The roles of reactive oxygen species (ROS) in the oxidative burst and pathogen killing are well known, but ROS also have important functions in extra-cellular and intra-cellular signalling. Iron deposition, resulting from venous reflux, primes macrophages towards a persistent inflammatory response, with ongoing stimulation by bacteria potentially playing a role. Generation of excessive ROS by activated inflammatory cells causes tissue destruction and disintegration of the dermis, and then at later stages, a failure to heal. Here, we review the evidence for ROS in CVU formation and in normal and delayed healing. We also discuss how ROS modulation might be used to influence the healing of these complex wounds, which cause long-term morbidity and are associated with a significant financial burden to healthcare systems.

Transforming growth factor-β in tissue fibrosis

TGF-β is extensively implicated in the pathogenesis of fibrosis. In fibrotic lesions, spatially restricted generation of bioactive TGF-β from latent stores requires the cooperation of proteases, integrins, and specialized extracellular matrix molecules. Although fibroblasts are major targets of TGF-β, some fibrogenic actions may reflect activation of other cell types, including macrophages, epithelial cells, and vascular cells. TGF-β–driven fibrosis is mediated through Smad-dependent or non-Smad pathways and is modulated by coreceptors and by interacting networks. This review discusses the role of TGF-β in fibrosis, highlighting mechanisms of TGF-β activation and signaling, the cellular targets of TGF-β actions, and the challenges of therapeutic translation.

Involvement of the Prion Protein in the Protection of the Human Bronchial Epithelial Barrier Against Oxidative Stress

Aim: Bronchial epithelium acts as a defensive barrier against inhaled pollutants and microorganisms. This barrier is often compromised in inflammatory airway diseases that are characterized by excessive oxidative stress responses, leading to bronchial epithelial shedding, barrier failure, and increased bronchial epithelium permeability. Among proteins expressed in the junctional barrier and participating to the regulation of the response to oxidative and to environmental stresses is the cellular prion protein (PrP^C). However, the role of PrP^C is still unknown in the bronchial epithelium. Herein, we investigated the cellular mechanisms by which PrP^C protein participates into the junctional complexes formation, regulation, and oxidative protection in human bronchial epithelium. Results: Both PrP^C messenger RNA and mature protein were expressed in human epithelial bronchial cells. PrP^C was localized in the apical domain and became lateral, at high degree of cell polarization, where it colocalized and interacted with adherens (E-cadherin/γ-catenin) and desmosomal (desmoglein/desmoplakin) junctional proteins. No interaction was detected with tight junction proteins. Disruption of such interactions induced the loss of the epithelial barrier. Moreover, we demonstrated that PrP^C protection against copper-associated oxidative stress was involved in multiple processes, including the stability of adherens and desmosomal junctional proteins. Innovation: PrP^C is a pivotal protein in the protection against oxidative stress that is associated with the degradation of adherens and desmosomal junctional proteins. Conclusion: Altogether, these results demonstrate that the loss of the integrity of the epithelial barrier by oxidative stress is attenuated by the activation of PrP^C expression, where deregulation might be associated with respiratory diseases.

Dexmedetomidine and Magnesium Sulfate: A Good Combination Treatment for Acute Lung Injury?

Objectives: In this study, we aimed to investigate the therapeutic effects of magnesium sulfate (MgSO₄) and dexmedetomidine (dex) in a model of acute lung injury (ALI). We determined whether concomitant administration decreased the inflammatory effects of hydrochloric acid (HCl)-induced ALI in a synergistic manner. Materials and Methods: In this study, 42 Sprague-Dawley rats were randomized into six groups: Group S (saline), Group SV (saline + mechanical ventilation), Group HCl (HCl), Group Dex (Dex), Group Mag (MgSO₄), and Group DM (Dex + MgSO₄). All groups except Group S were mechanically ventilated prior to HCl-induced ALI. Saline or HCl was administered via tracheostomy. Prior to treatment, HCl was administered to Group HCl, Group Dex, Group Mag, and Group DM to induce ALI. Dex and MgSO₄ were administered intraperitoneally. The rats were monitored for 4 h after treatment to measure oxidative stress parameters in blood, and prolidase enzyme activity. Lung tissue damage were determined via histopathology. Results: A significant increase in heart rate and rapid desaturation was observed in HCl-administered groups. Treatment administration decreased the pulse values. Increased saturation values and decreased oxidative stress indices were observed in groups that were subsequently administered​ Dex and MgSO₄. Serum prolidase activity increased significantly in Group HCl. Severe pathological findings were detected following HCl-induced ALI. Group Mag showed greater improvement in the pathology of HCl-induced ALI than did Group Dex. Administration of both Dex and MgSO₄ did not improve the pathological scores. Conclusions: The antioxidant and anti-inflammatory effects of Dex and MgSO₄ ameliorated the detrimental effects of HCI-induced ALI. However, adverse effects on hemodynamics and lung damage were observed when the two drugs were administered together.

Protective effect of SIRT3 on acute lung injury by increasing manganese superoxide dismutase-mediated antioxidation

Prolonged exposure to hyperoxia results in acute lung injury (ALI). Pulmonary damage caused by oxygen toxicity occurs due to the generation of reactive oxygen species and subsequent formation of more potent oxidants. The present study demonstrated that sirtuin 3 (SIRT3) may attenuate hyperoxia‑induced ALI due to its potential antioxidative effect. In the present study, a hyperoxia‑induced acute lung injury mouse model, reverse transcription‑quantitative polymerase chain reaction, western blotting, retroviral mediated gene over‑expression and knockdown assays revealed that the expression of SIRT3 in the lung tissue of mice with hyperoxia‑induced ALI was decreased and overexpression of SIRT3 may significantly reduce hyperoxia‑induced ALI, as reflected by decreases in protein concentration, infiltrated neutrophils in bronchoalveolar lavage (BAL) fluid and wet/dry ratio of lung tissues. Furthermore, overexpression of SIRT3 increased the protein levels and enzymatic activity of manganese superoxide dismutase (MnSOD), and inhibited oxidative stress in the lungs of ALI mice. Additionally, the current study demonstrated that SIRT3 promoted the expression of MnSOD, and this regulation was crucial for the protective effect of SIRT3 on hyperoxia‑induced ALI. In summary, the results of the current study indicated that SIRT3 overexpression may effectively ameliorate hyperoxia‑induced ALI in mice, which indicates a potential application for SIRT3‑based gene therapy to treat clinical adult respiratory distress syndrome.

Reactive Oxygen Species and NOX Enzymes Are Emerging as Key Players in Cutaneous Wound Repair

Our understanding of the role of oxygen in cell physiology has evolved from its long-recognized importance as an essential factor in oxidative metabolism to its recognition as an important player in cell signaling. With regard to the latter, oxygen is needed for the generation of reactive oxygen species (ROS), which regulate a number of different cellular functions including differentiation, proliferation, apoptosis, migration, and contraction. Data specifically concerning the role of ROS-dependent signaling in cutaneous wound repair are very limited, especially regarding wound contraction. In this review we provide an overview of the current literature on the role of molecular and reactive oxygen in the physiology of wound repair as well as in the pathophysiology and therapy of chronic wounds, especially under ischemic and hyperglycemic conditions.

Silver nanoparticles enhance wound healing in zebrafish (Danio rerio)

Silver nanoparticles (AgNPs) were successfully synthesized by a chemical reduction method, physico-chemically characterized and their effect on wound-healing activity in zebrafish was investigated. The prepared AgNPs were circular-shaped, water soluble with average diameter and zeta potential of 72.66 nm and -0.45 mv, respectively. Following the creation of a laser skin wound on zebrafish, the effect of AgNPs on wound-healing activity was tested by two methods, direct skin application (2 μg/wound) and immersion in a solution of AgNPs and water (50 μg/L). The zebrafish were followed for 20 days post-wounding (dpw) by visual observation of wound size, calculating wound healing percentage (WHP), and histological examination. Visually, both direct skin application and immersion AgNPs treatments displayed clear and faster wound closure at 5, 10 and 20 dpw compared to the controls, which was confirmed by 5 dpw histology data. At 5 dpw, WHP was highest in the AgNPs immersion group (36.6%) > AgNPs direct application group (23.7%) > controls (18.2%), showing that WHP was most effective in fish immersed in AgNPs solution. In general, exposure to AgNPs induced gene expression of selected wound-healing-related genes, namely, transforming growth factor (TGF-β), matrix metalloproteinase (MMP) -9 and -13, pro-inflammatory cytokines (IL-1β and TNF-α) and antioxidant enzymes (superoxide dismutase and catalase), which observed differentiation at 12 and 24 h against the control; but the results were not consistently significant, and many either reached basal levels or were down regulated at 5 dpw in the wounded muscle. These results suggest that AgNPs are effective in acceleration of wound healing and altered the expression of some wound-healing-related genes. However, the detailed mechanism of enhanced wound healing remains to be investigated in fish.

Transforming growth factor alpha is a critical mediator of radiation lung injury

Radiation fibrosis of the lung is a late toxicity of thoracic irradiation. Epidermal growth factor (EGF) signaling has previously been implicated in radiation lung injury. We hypothesized that TGF-α, an EGF receptor ligand, plays a key role in radiation-induced fibrosis in lung. Mice deficient in transforming growth factor (TGF-α(-/-)) and control C57Bl/6J (C57-WT) mice were exposed to thoracic irradiation in 5 daily fractions of 6 Gy. Cohorts of mice were followed for survival (n ≥ 5 per group) and tissue collection (n = 3 per strain and time point). Collagen accumulation in irradiated lungs was assessed by Masson's trichrome staining and analysis of hydroxyproline content. Cytokine levels in lung tissue were assessed with ELISA. The effects of TGF-α on pneumocyte and fibroblast proliferation and collagen production were analyzed in vitro. Lysyl oxidase (LOX) expression and activity were measured in vitro and in vivo. Irradiated C57-WT mice had a median survival of 24.4 weeks compared to 48.2 weeks for irradiated TGF-α(-/-) mice (P = 0.001). At 20 weeks after irradiation, hydroxyproline content was markedly increased in C57-WT mice exposed to radiation compared to TGF-α(-/-) mice exposed to radiation or unirradiated C57-WT mice (63.0, 30.5 and 37.6 μg/lung, respectively, P = 0.01). C57-WT mice exposed to radiation had dense foci of subpleural fibrosis at 20 weeks after exposure, whereas the lungs of irradiated TGF-α (-/-) mice were largely devoid of fibrotic foci. Lung tissue concentrations of IL-1β, IL-4, TNF-α, TGF-β and EGF at multiple time points after irradiation were similar in C57-WT and TGF-α(-/-) mice. TGF-α in lung tissue of C57-WT mice rose rapidly after irradiation and remained elevated through 20 weeks. TGF-α(-/-) mice had lower basal LOX expression than C57-WT mice. Both LOX expression and LOX activity were increased after irradiation in all mice but to a lesser degree in TGF-α(-/-) mice. Treatment of NIH-3T3 fibroblasts with TGF-α resulted in increases in proliferation, collagen production and LOX activity. These studies identify TGF-α as a critical mediator of radiation-induced lung injury and a novel therapeutic target in this setting. Further, these data implicate TGF-α as a mediator of collagen maturation through a TGF-β independent activation of lysyl oxidase.

Non-thermal dielectric barrier discharge plasma induces angiogenesis through reactive oxygen species

Vascularization plays a key role in processes such as wound healing and tissue engineering. Non-thermal plasma, which primarily produces reactive oxygen species (ROS), has recently emerged as an efficient tool in medical applications including blood coagulation, sterilization and malignant cell apoptosis. Liquids and porcine aortic endothelial cells were treated with a non-thermal dielectric barrier discharge plasma in vitro. Plasma treatment of phosphate-buffered saline (PBS) and serum-free medium increased ROS concentration in a dose-dependent manner, with a higher concentration observed in serum-free medium compared with PBS. Species concentration inside cells peaked 1 h after treatment, followed by a decrease 3 h post treatment. Endothelial cells treated with a plasma dose of 4.2 J cm(-2) had 1.7 times more cells than untreated samples 5 days after plasma treatment. The 4.2 J cm(-2) plasma dose increased two-dimensional migration distance by 40 per cent compared with untreated control, while the number of cells that migrated through a three-dimensional collagen gel increased by 15 per cent. Tube formation was also enhanced by plasma treatment, with tube lengths in plasma-treated samples measuring 2.6 times longer than control samples. A fibroblast growth factor-2 (FGF-2) neutralizing antibody and ROS scavengers abrogated these angiogenic effects. These data indicate that plasma enhanced proliferation, migration and tube formation is due to FGF-2 release induced by plasma-produced ROS. Non-thermal plasma may be used as a potential tool for applying ROS in precise doses to enhance vascularization.

Diverse injurious stimuli reduce protein tyrosine phosphatase-μ expression and enhance epidermal growth factor receptor signaling in human airway epithelia

In response to injury, airway epithelia utilize an epidermal growth factor (EGF) receptor (EGFR) signaling program to institute repair and restitution. Protein tyrosine phosphatases (PTPs) counterregulate EGFR autophosphorylation and downstream signaling. PTPμ is highly expressed in lung epithelia and can be localized to intercellular junctions where its ectodomain homophilically interacts with PTPμ ectodomain expressed on neighboring cells. We asked whether PTPμ expression might be altered in response to epithelial injury and whether altered PTPμ expression might influence EGFR signaling. In A549 cells, diverse injurious stimuli dramatically reduced PTPμ protein expression. Under basal conditions, small interfering RNA (siRNA)-induced silencing of PTPμ increased EGFR Y992 and Y1068 phosphorylation. In the presence of EGF, PTPμ knockdown increased EGFR Y845, Y992, Y1045, Y1068, Y1086, and Y1173 but not Y1148 phosphorylation. Reduced PTPμ expression increased EGF-stimulated phosphorylation of Y992, a docking site for phospholipase C (PLC)γ(1), activation of PLCγ(1) itself, and increased cell migration in both wounding and chemotaxis assays. In contrast, overexpression of PTPμ decreased EGF-stimulated EGFR Y992 and Y1068 phosphorylation. Therefore, airway epithelial injury profoundly reduces PTPμ expression, and PTPμ depletion selectively increases phosphorylation of specific EGFR tyrosine residues, PLCγ(1) activation, and cell migration, providing a novel mechanism through which epithelial integrity may be restored.

Thrombospondin-1 opens the paracellular pathway in pulmonary microvascular endothelia through EGFR/ErbB2 activation

Thrombospondin-1 (TSP1) is a multidomain protein that contains epidermal growth factor (EGF)-like repeats that indirectly activate the EGF receptor (EGFR) and selected downstream signaling pathways. In these studies, we show that TSP1 opens the paracellular pathway in human lung microvascular endothelial cells (HMVEC-Ls) in a dose-, time-, and protein tyrosine kinase (PTK)-dependent manner. TSP1 increased tyrosine phosphorylation of proteins enriched to intercellular boundaries including the zonula adherens (ZA) proteins, vascular endothelial-cadherin, γ-catenin, and p120 catenin. In HMVEC-Ls, EGFR and ErbB2 are expressed at low levels, and both heterodimerize and tyrosine autophosphorylate in response to TSP1. Prior EGFR-selective PTK inhibition with AG1478 or ErbB2-selective PTK inhibition with AG825 protected against TSP1-induced tyrosine phosphorylation of ZA proteins and barrier disruption. Preincubation of HMVEC-Ls with an EGFR ectodomain-blocking antibody also prevented TSP1-induced opening of the paracellular pathway. Therefore, in HMVEC-Ls, TSP1 increases tyrosine phosphorylation of ZA proteins and opens the paracellular pathway, in part, through EGFR/ErbB2 activation. Surprisingly, recombinant TSP1 EGF-like repeats 1-3 and the high-affinity EGFR ligands, EGF, TGF-α, and amphiregulin, each failed to increase paracellular permeability. However, HMVEC-Ls in which EGFR was overexpressed became responsive to the EGF-like repeats of TSP1 as well as to EGF. These studies indicate that TSP1 disrupts the endothelial barrier through EGFR/ErbB2 activation although additional signals are necessary in cells with low receptor expression.

New pharmacotherapy for airway mucus hypersecretion in asthma and COPD: targeting intracellular signaling pathways

Airway mucus hypersecretion is a pathophysiological feature of asthma and chronic obstructive pulmonary disease (COPD). The hypersecretion is associated with phenotypic changes in the airways, notably, increases in the number of surface epithelial goblet cells (hyperplasia) and in the size of the submucosal glands (hypertrophy). The hyperplasia and hypertrophy are associated with increased production of mucin, the gel-forming component of mucus. The excess mucus production contributes to morbidity and mortality in many patients, particularly in those with more severe disease. Although current pharmacotherapy is effective in clinical management of patients with stable asthma, severe asthma is poorly treated and there is no current drug treatment for COPD. In neither disease is there specific, effective pharmacotherapy for the hypersecretion. Consequently, identification of potential drug targets for treatment of hypersecretion in asthma and COPD is warranted. The inflammatory mediators and the associated intracellular signaling pathways underlying upregulation of mucin synthesis and development of goblet cell hyperplasia are gradually being elucidated. These include Th2 cytokines (predominantly IL-9 and IL-13), and IL-1 beta, tumor necrosis factor-alpha (TNF-alpha) and cyclooxygenase (COX)-2. IL-9 may act predominantly via calcium-activated chloride channels (CLCA), IL-13 via STAT-6 and FOXA2, TNF-alpha via NF-kappaB, and IL-1 beta via COX-2. Epidermal growth factor receptor (EGF-R) signaling and FOXA2 appear to be convergent intracellular pathways for a number of inflammatory mediators, with EGF-R upregulated in the airways of asthmatic and COPD patients. Thus, preclinical studies have clearly identified a number of intracellular signaling pathways as possible targets for pharmacotherapy of airway mucus hypersecretion in asthma and COPD. Of these, the EGF-R and Th2 cytokine pathways may have the greatest potential for inhibition of excessive mucus production. However, because these targets are so often intimately involved with different aspects of airway (and systemic) homeostasis, there is potential for development of unwanted side effects with drug intervention. Thus, translation of the promising preclinical studies to the clinic will depend on development of drug moieties with low off-target activity. This may be accomplished by maximizing airway selectivity, which may be facilitated by appropriate delivery device design.

Postinfarct intramyocardial injection of mesenchymal stem cells pretreated with TGF-alpha improves acute myocardial function

Stem cell-based therapies offer promising potential for myocardial infarction (MI), but endogenous molecules released in response to injury likely impair posttransplantation stem cell function. Stem cell-mediated cardioprotection occurs in part via paracrine effects, and transforming growth factor-alpha (TGF-alpha) has been shown to enhance paracrine function. However, it is unknown whether pretreating stem cells with TGF-alpha increases stem cell-mediated cardioprotection after acute MI. Mesenchymal stem cells (MSCs) were treated with TGF-alpha (250 ng/ml) for 24 h. Adult male Sprague-Dawley rat hearts were isolated and perfused using the Langendorff method. MI was induced by ligating the left anterior descending coronary artery. Postligation (30 min), vehicle or 1 x 10(6) MSCs with or without pretreatment were injected in the infarct border zones, and the hearts were perfused for an additional 60 min. Left ventricular function was continuously measured, and infarct size was assessed with Evans blue dye and 2,3,5-triphenyltetrazolium chloride staining. Myocardial production of interleukin (IL)-1beta and IL-6 and caspase 3 activation was also measured. Left ventricular function decreased significantly following coronary artery ligation but improved following injection of untreated MSCs and to a greater extent after injection of pretreated MSCs. In addition, the infarct area, myocardial caspase 3 activation, and IL-6 production were lowest in hearts injected with pretreated cells. Intramyocardial injection of TGF-alpha-pretreated MSCs after acute MI is associated with increased myocardial function and decreased myocardial injury. This strategy may be useful for optimizing the therapeutic efficacy of stem cells for the treatment of acute MI.

The counteradhesive proteins, thrombospondin 1 and SPARC/osteonectin, open the tyrosine phosphorylation-responsive paracellular pathway in pulmonary vascular endothelia

Counteradhesive proteins are a group of genetically and structurally distinct multidomain proteins that have been grouped together for their ability to inhibit cell-substrate interactions. Three counteradhesive proteins that influence endothelial cell behavior include thrombospondin (TSP)1, (SPARC) (Secreted Protein Acidic and Rich in Cysteine), also known as osteonectin, and tenascin. More recently, these proteins have been shown to regulate not only cell-matrix interactions but cell-cell interactions as well. TSP1 increases tyrosine phosphorylation of components of the cell-cell adherens junctions or zonula adherens (ZA) and opens the paracellular pathway in human lung microvascular endothelia. The epidermal growth factor (EGF)-repeats of TSP1 activate the (EGF) receptor (EGFR) and ErbB2, and these two receptor protein tyrosine kinases (PTK)s participate in ZA protein tyrosine phosphorylation and barrier disruption in response to the TSP1 stimulus. For the barrier response to TSP1, EGFR/ErbB2 activation is necessary but insufficient. Protein tyrosine phosphatase (PTP)mu counter-regulates phosphorylation of selected tyrosine residues within the cytoplasmic domain of EGFR. Although tenascin, like TSP1, also contains EGF-like repeats and is known to activate EGFR, whether it also opens the paracellular pathway is unknown. In addition to TSP1, tenascin, and the other TSP family members, there are numerous other proteins that also contain EGF-like repeats and participate in hemostasis, wound healing, and tissue remodeling. EGFR not only responds to direct binding of EGF motif-containing ligands but can also be transactivated by a wide range of diverse stimuli. In fact, several established mediators of increased vascular permeability and/or lung injury, including thrombin, tumor necrosis factor-alpha, platelet-activating factor, bradykinin, angiopoietin, and H(2)O(2), transactivate EGFR. It is conceivable that EGFR serves a pivotal signaling role in a final common pathway for the pulmonary response to selected injurious stimuli. SPARC/Osteonectin also increases tyrosine phosphorylation of ZA proteins and opens the endothelial paracellular pathway in a PTK-dependent manner. The expression of the counteradhesive proteins is increased in response to a wide range of injurious stimuli. It is likely that these same molecules participate in the host response to acute lung injury and are operative during the barrier response within the pulmonary microvasculature.

Regulation of alveologenesis: clinical implications of impaired growth

During its development that begins in intrauterine life, the lung is transformed from a simple epithelial lined sac that emerges from the foregut into a complex arrangement of blood vessels, airways, and alveoli that make up the mature lung structure. This remarkable transformation that continues for several years postnatally, is achieved by the influence of several genes, transcription factors, growth factors and hormones upon the cells and proteins of the lung bud. A seminal event in this process is the formation of the air-blood barrier within the alveolar wall, an evolutionary modification that permits independent air-breathing existence in mammals. Molecular biological techniques have enabled elucidation of the mechanistic pathways contributing to alveologenesis and have provided probable molecular bases for examples of impaired alveologenesis encountered by the paediatric pathologist.

Redox signals in wound healing

Physical trauma represents one of the most primitive challenges that threatened survival. Healing a problem wound requires a multi-faceted comprehensive approach. First and foremost, the wound environment will have to be made receptive to therapies. Second, the appropriate therapeutic regimen needs to be identified and provided while managing systemic limitations that could secondarily limit the healing response. Unfortunately, most current solutions seem to aim at designing therapeutic regimen with little or no consideration of the specific details of the wound environment and systemic limitations. One factor that is centrally important in making the wound environment receptive is correction of wound hypoxia. Recent work have identified that oxygen is not only required to disinfect wounds and fuel healing but that oxygen-dependent redox-sensitive signaling processes represent an integral component of the healing cascade. Over a decade ago, it was proposed that in biological systems oxidants are not necessarily always the triggers for oxidative damage and that oxidants such as H2O2 could actually serve as signaling messengers and drive several aspects of cellular signaling. Today, that concept is much more developed and mature. Evidence supporting the role of oxidants such as H2O2 as signaling messenger is compelling. A complete understanding of the continuum between the classical and emergent roles of oxygen requires a thorough consideration of current concepts in redox biology. The objective of this review is to describe our current understanding of how redox-sensitive processes may drive dermal tissue repair.

Effect of a Biological Response Modifier on Expression of Growth Factors and Cellular Proliferation at Drying Off

Agents that increase natural protective mechanisms have been proposed for the prevention and treatment of intramammary infections. Staphylococcus aureus is a major pathogen causing primarily subclinical chronic mastitis that responds poorly to antibiotic therapy. The objectives of this study were to describe the effects of a single intramammary infusion of a lipopolysaccharide-based biological response modifier (BRM) on mammary epithelial cellular proliferation and expression of insulin-like growth factor-I (IGF-I) and vascular endothelial growth factor (VEGF) in uninfected and Staph. aureus-infected bovine mammary glands during involution. Three groups of 12 cows, 6 Staph. aureus-infected and 6 uninfected, were infused with BRM or placebo in 2 mammary quarters and killed at 7, 14, and 21 d of involution. The proportion of infected quarters, mammary cell proliferation, and IGF-I and VEGF expression were evaluated. Biological response modifier treatment decreased the proportion of Staph. aureus-infected mammary quarters at 7 d of involution, but a similar number of isolations were observed at 14 and 21 d of involution in either treated or control quarters. The percentage of proliferating mammary epithelial cells was higher in infected than uninfected quarters at every observation period, irrespective of the treatment administered, whereas uninfected BRM-treated quarters showed increased cell proliferation at 7 d of involution. Insulin-like growth factor-I expression in uninfected quarters was not affected by treatment and showed a decrease at 21 d of involution. Expression of IGF-I was greater in infected than uninfected quarters at every observation period, irrespective of the treatment received. Expression of VEGF was greater in BRM-treated uninfected quarters at 7 d of involution compared with controls. In infected quarters, VEGF expression was lowest in BRM-treated quarters at 7 d of involution and increased throughout the observation period. Conversely, untreated infected quarters showed the highest VEGF expression at 7 d and decreased at 21 d of involution. Mammary cell proliferation and expression of IGF-I and VEGF were increased in Staph. aureus-infected quarters. Increased mammary cell proliferation and VEGF expression were observed in BRM-treated quarters during the first week of involution.

TGF-alpha and ErbB2 production in synovial joint tissue: increased expression in arthritic joints

OBJECTIVE

Cell types present in synovial joint tissues and during synovitis are known to produce epidermal growth factor receptor (EGFR)/ErbB-1/HER-1 and the potent EGFR-ligand transforming growth factor-alpha (TGF-alpha) in vitro. Concomitant expression of TGF-alpha, EGFR, and ErbB2 gives a strong proliferative drive in vitro and in vivo. However, the presence of TGF-alpha and members of the EGFR/EGFR-ligand family has not been thoroughly investigated in joint tissue in vivo. We aimed to determine whether TGF-alpha, EGFR, and ErbB2 are present in human synovial joints, especially during rheumatoid arthritis (RA).

METHODS

TGF-alpha protein was immunodetected in knee synovial fluid (SF) collected from 23 RA patients, eight patients with other arthritic conditions, two osteoarthritis (OA) patients, and six post-traumatic patients (control). TGF-alpha mRNA and TGF-alpha, ErbB2, EGFR, and CD68 immunoreactivity were detected in knee synovial biopsies (6 RA/2 OA/6 control) using in situ hybridization and immunohistochemistry. TGF-alpha mRNA was determined in SF cells by reverse transcription polymerase chain reaction (RT-PCR) and/or the Northern blot technique.

RESULTS

TGF-alpha protein was found in the synovial membrane (SM) and in the majority of SF samples. TGF-alpha levels were significantly higher (p < 0.001) in SF of RA patients than controls, TGF-alpha protein and mRNA were increased and more widespread in SM of RA patients. In addition, white blood cells collected from RA SF expressed TGF-alpha mRNA. Immunoreactivity for ErbB2 was found in SM and was more widespread in RA patients than in controls.

CONCLUSION

The presence of TGF-alpha in normal SF and SM may indicate a physiological maintenance function. The increased expression of TGF-alpha and ErbB2 in RA SF and SM may give rise to an abnormal growth pattern, contributing to inflammatory synovial hyperplasia.

TGF-alpha perturbs surfactant homeostasis in vivo

To determine potential relationships between transforming growth factor (TGF)-alpha and surfactant homeostasis, the metabolism, function, and composition of surfactant phospholipid and proteins were assessed in transgenic mice in which TGF-alpha was expressed in respiratory epithelial cells. Secretion of saturated phosphatidylcholine was decreased 40-60% by expression of TGF-alpha. Although SP-A, SP-B, and SP-C mRNA levels were unchanged by expression of TGF-alpha, SP-A and SP-B content in bronchoalveolar lavage fluid was decreased. The minimum surface tension of surfactant isolated from the transgenic mice was significantly increased. Incubation of cultured normal mice type II cells with TGF-alpha in vitro did not change secretion of surfactant phosphatidylcholine and SP-B, indicating that TGF-alpha does not directly influence surfactant secretion. Expression of a dominant negative (mutant) EGF receptor in the respiratory epithelium blocked the TGF-alpha-induced changes in lung morphology and surfactant secretion, indicating that EGF receptor signaling in distal epithelial cells was required for TGF-alpha effects on surfactant homeostasis. Because many epithelial cells were embedded in fibrotic lesions caused by TGF-alpha, changes in surfactant homeostasis may at least in part be influenced by tissue remodeling that results in decreased surfactant secretion. The number of nonembedded type II cells was decreased 30% when TGF-alpha was expressed during development and was increased threefold by TGF-alpha expression in adulthood, suggesting possible alteration of type II cells on surfactant metabolism in the adult lung. Abnormalities in surfactant function and decreased surfactant level in the airways may contribute to the pathophysiology induced by TGF-alpha in both the developing and adult lung.

Transforming growth factor-α and oral fibroma: immunohistochemical and in situ hybridization study

PURPOSE

Transforming growth factor-alpha (TGF-alpha) is usually expressed in cell lines derived from sarcomas. It is known as a mitogen for fibroblasts. The aim of this study was to determine whether there were any differences in the expression pattern of TGF-alpha between normal oral mucosa and oral fibroma.

PATIENTS AND METHODS

Fourteen pathologic specimens (6 males and 8 females; 37.2 +/- 23.2 years) and 10 normal oral mucosal specimens (5 females and 5 males; 43.8 +/- 17.7 years) were used for this study. Identification of TGF-alpha was sought by using immunohistochemistry and in situ hybridization.

RESULTS

The samples from normal oral mucosa did not express TGF-alpha. One sample from oral fibroma did not express TGF-alpha (7.1%). Five samples from oral fibroma expressed TGF-alpha sparsely (35.7%). Eight samples showed diffuse expression of TGF-alpha (57.1%). The immunopositive reaction to TGF-alpha in oral fibroma was localized in the basal layer and the fibroblasts that resided beneath the epithelium. This pattern was also shown in the in situ hybridization study as well.

CONCLUSION

TGF-alpha is expressed in oral fibromas. It suggested that TGF-alpha might play a role in fibroblast proliferation in oral fibromas.

Novel mechanisms of sublethal oxidant toxicity: induction of premature senescence in human fibroblasts confers tumor promoter activity

Aging is the highest risk factor for cancer. Although oxidants are thought to contribute to both aging and cancer, the interplay between oxidative stress, aging, and cancer has not been well studied. Human diploid fibroblasts (HDFs) undergo premature senescence in response to sublethal doses of H(2)O(2). To test the hypothesis that senescent or senescent-like HDFs function as a tumor promoter, we have employed an in vitro skin tumor promotion model, in which colony formation is measured using initiated mouse keratinocyte 308 cells seeded at clonal density. 308 cells form colonies when co-cultured with normal HDFs only in the presence of the tumor promoter phorbol 12-myristate 13-acetate (TPA), which induces an average of 5.75 colonies. When co-cultured with H(2)O(2)-treated HDFs, 308 cells form an average of 30.3 colonies. To understand the mechanism behind this phenomenon, we tested whether conditioned medium of HDFs, HDF extracellular matrix (ECM), density of HDFs, or the contact between keratinocytes and HDFs plays a role in 308 cell colony formation. The conditioned medium from prematurely senescent cells resulted in an average of eightfold more 308 cell colonies formed than the conditioned medium from normal HDFs, and the growth-promoting effect of the conditioned medium was trypsin sensitive. The ECM alone was not able to induce 308 cell colony formation. Increasing the density of normal HDFs or contact with normal HDFs but not senescent-like HDFs was inhibitory to the growth of 308 cells. Measurement of Connexin 43 indicated a decreased expression of the protein, which suggests an impaired gap junction communication in senescent-like HDFs. We conclude that H(2)O(2)-treated fibroblasts not only lose contact inhibition of the growth of initiated keratinocytes perhaps related to reduced gap junction communication but also increase production of secreted protein factors to enhance the growth of 308 keratinocytes.

The general case for redox control of wound repair

The orthodox view has been that reactive oxygen species are primarily damaging to cells. There is general agreement that while high (3%) doses of H(2)O(2) may serve as a clinical disinfectant, its overall effect on healing is not positive. Current work shows that at very low concentrations, reactive oxygen species may regulate cellular signaling pathways by redox-dependent mechanisms. Recent discoveries show that almost all cells of the wound microenvironment contain specialized enzymes that utilize O(2) to generate reactive oxygen species. Numerous aspects of wound healing are subject to redox control. An understanding of how endogenous reactive oxygen species are generated in wound-related cells may influence the healing process and could result in new redox-based therapeutic strategies. Current results with growth factor therapy of wounds have not met clinical expectations. Many of these growth factors, such as platelet-derived growth factor, rely on reactive oxygen species for functioning. Redox-based strategies may serve as effective adjuncts to jump-start healing of chronic wounds. The understanding of wound-site redox biology is also likely to provide novel insights into the fundamental mechanisms that would help to optimize conditions for oxygen therapy. While a window of therapeutic opportunity seems to exist under conditions of low concentrations of reactive oxygen species, high levels may complicate regeneration and remodeling of nascent tissue.

Vanadium-induced HB-EGF expression in human lung fibroblasts is oxidant dependent and requires MAP kinases

Vanadium pentoxide (V(2)O(5)) is a transition metal derived from the burning of petrochemicals that causes airway fibrosis and remodeling. Vanadium compounds activate many intracellular signaling pathways via the generation of hydrogen peroxide (H(2)O(2)) or other reactive oxygen species. In this study, we investigated the regulation of heparin-binding epidermal growth factor-like growth factor (HB-EGF) in human lung fibroblasts after V(2)O(5) treatment. V(2)O(5)-induced HB-EGF mRNA expression was abolished by N-acetyl-l-cysteine, suggesting an oxidant-mediated effect. Exogenous H(2)O(2) (>10 microM) mimicked the effect of V(2)O(5) in upregulating HB-EGF expression. Fibroblasts spontaneously released low levels of H(2)O(2) (1-2 microM), and the addition of V(2)O(5) depleted the endogenous H(2)O(2) pool within minutes. V(2)O(5) caused a subsequent increase of H(2)O(2) into the culture medium at 12 h. However, the burst of V(2)O(5)-induced H(2)O(2) occurred after V(2)O(5)-induced HB-EGF mRNA expression at 3 h, indicating that the V(2)O(5)-stimulated H(2)O(2) burst did not mediate HB-EGF expression. Either V(2)O(5) or H(2)O(2) activated ERK-1/2 and p38 MAP kinase. Inhibitors of the ERK-1/2 pathway (PD-98059) or p38 MAP kinase (SB-203580) significantly reduced either V(2)O(5)- or H(2)O(2)-induced HB-EGF expression. These data indicate that vanadium upregulates HB-EGF via ERK and p38 MAP kinases. The induction of HB-EGF is not related to a burst of H(2)O(2) in V(2)O(5) treated cells, yet the action of V(2)O(5) in upregulating HB-EGF is oxidant dependent and could be due to the reaction of V(2)O(5) with endogenous H(2)O(2).

Overexpression of TGF-alpha increases lung tissue hysteresivity in transgenic mice

Increased transforming growth factor (TGF)-alpha has been observed in neonatal chronic lung disease. Lungs of transgenic mice that overexpress TGF-alpha develop enlarged air spaces and pulmonary fibrosis compared with wild-type mice. We hypothesized that these pathological changes may alter the mechanical coupling of viscous and elastic forces within lung parenchyma. Respiratory impedance was measured in open-chested, tracheostomized adult wild-type and TGF-alpha mice by using the forced oscillation technique (0.25-19.63 Hz) delivered by flexiVent (Scireq, Montreal, PQ). Estimates of airway resistance (Raw), inertance (I), and the coefficients of tissue damping (G(L)) and tissue elastance (H(L)) were obtained by fitting a model to each impedance spectrum. Hysteresivity (eta) was calculated as G(L)/H(L). There was a significant increase in eta (P < 0.01) and a trend to a decrease in H(L) (P = 0.07) of TGF-alpha mice compared with the wild-type group. There was no significant change in Raw, I, or G(L). Structural abnormality present in the lungs of adult TGF-alpha mice alters viscoelastic coupling of the tissues, as evidenced by a change in eta.

Mechanisms of repair and remodeling following acute lung injury

At present, we largely lack the ability to correlate the clinical course of ARDS patients with potential factors involved in the biochemical and cellular basis of lung repair. This requires very large patient databases with measurement of many biochemical parameters. Important mechanistic determinants during the repair phase can be sought by correlation with late outcomes, but a large-scale cooperative effort among multiple centers with sharing of follow-up data and patient specimens is essential. We also lack detailed human histologic material from many phases of ARDS and, particularly, know little of the long-term morphologic impact of ARDS in survivors. Establishment of a national registry that follows ARDS survivors and that would seek their cooperation in advance in obtaining autopsy specimens when they die of other causes would be very valuable. Correlating the pathology with their pulmonary function during recovery would give important insights into the reasons for the different patterns of abnormal pulmonary functions. The factors that determine the success of repair are of critical importance in testing new ARDS treatment strategies. Would accelerating the resolution of alveolar edema alter the course of subsequent fibrosis and inflammation? Does surfactant replacement therapy--a costly proposition in adults with ARDS--lead to better long-term outcomes in survivors? How much should we worry about the use of high levels of oxygen for support of arterial partial pressure of oxygen? Is it better to accept hyperoxia to avoid pressure or volume trauma induced by mechanical ventilation with higher minute ventilations? These major management issues all may affect the success of the late repair and recovery process. Intervention trials need to examine the long-term physiologic and functional outcomes.

Oxidative stress causes mucin synthesis via transactivation of epidermal growth factor receptor: role of neutrophils

Oxidative stress has been implicated in the pathogenesis of inflammatory diseases of airways. Here we show that oxidative stress causes ligand-independent activation of epidermal growth factor receptors (EGFR) and subsequent activation of mitogen-activated protein kinase kinase (MEK)-p44/42 mitogen-activated protein kinase (p44/42mapk), resulting in mucin synthesis in NCI-H292 cells. Exogenous hydrogen peroxide and neutrophils activated by IL-8, FMLP, or TNF-alpha increased EGFR tyrosine phosphorylation and subsequent activation of p44/42mapk and up-regulated the expression of MUC5AC at both mRNA and protein levels in NCI-H292 cells. These effects were blocked by selective EGFR tyrosine kinase inhibitors (AG1478, BIBX1522) and by a selective MEK inhibitor (PD98059), whereas a selective platelet-derived growth factor receptor tyrosine kinase inhibitor (AG1295), a selective p38 MAPK inhibitor (SB203580), and a negative compound of tyrosine kinase inhibitors (A1) were without effect. Neutrophil supernatant-induced EGFR tyrosine phosphorylation, activation of p44/42mapk, and MUC5AC synthesis were inhibited by antioxidants (N-acetyl-cysteine, DMSO, dimethyl thiourea, or superoxide dismutase); neutralizing Abs to EGFR ligands (EGF and TGF-alpha) were without effect, and no TGF-alpha protein was found in the neutrophil supernatant. In contrast, the EGFR ligand, TGF-alpha, increased EGFR tyrosine phosphorylation, activation of p44/42mapk, and subsequent MUC5AC synthesis, but these effects were not inhibited by antioxidants. These results implicate oxidative stress in stimulating mucin synthesis in airways and provide new therapeutic approaches in airway hypersecretory diseases.

TGFbeta isoforms and decorin gene expression are modified in fibroblasts obtained from non-syndromic cleft lip and palate subjects

Interaction between extracellular matrix (ECM) and cytokines is thought to be crucial for palatal development. The localization of transforming growth factors (TGFalpha and TGFbeta isoforms) in craniofacial tissues suggests that they carry out multiple functions during development. In the present report, we studied TGFalpha, TGFbeta1, and TGFbeta3 expressions and their effects on ECM macromolecule production of normal and cleft palatal fibroblasts in vitro, to investigate the mechanisms by which the phenotypic modulation of fibroblasts occurs during the cleft palate process. The results indicated that, while TGFalpha mRNA was not evidenced in CLP or normal fibroblasts, a reduced TGFbeta1 hybridization signal was detected in CLP fibroblasts. In addition, these secreted more active TGFbeta3 than TGFbeta1, as evaluated in a biological assay. The CLP phenotype, which differed from the normal one because of its higher PG decorin expression and greater production of GAG and collagen, was further modified by the addition of growth factors. In fact, in CLP fibroblasts, TGFalpha and TGFbeta1 down-regulated PG decorin transcript, TGFbeta1 increased collagen and GAG in both cellular and extracellular compartments, and TGFbeta3 promoted secretory processes of cells. In conclusion, the data represent the first report in a human model in vitro that TGFbeta1 and beta3 are differently expressed and are correlated to the CLP phenotype. Thus, strength is given to the hypothesis that TGFbeta isoforms are the potential inducers of phenotypic expression in palatal fibroblasts during development and that an autocrine growth factor production mechanism may be responsible for the phenotypic modifications.

Developmental shift in the relative percentages of lung fibroblast subsets: role of apoptosis postseptation

We have used the lipophilic, fluorescent dye Nile red and flow cytometry to identify and isolate two rat lung fibroblast subsets, lipid-containing interstitial cells (LICs) and non-LICs (NLICs) and to quantitate developmental changes in the relative percentages of these subsets. A significant decrease was observed in the percentage of LICs (from 79.0 +/- 3.8% on postnatal day 4 to 28.6 +/- 4.2% on day 30; P < 0.0001). To determine whether one or both subsets undergo apoptosis postseptation, fibroblasts from 16- to 18-day rats were treated with BODIPY-conjugated dUTP to label DNA strand breaks, which were then quantitated by flow cytometry. Apoptotic cells were judged to be predominantly LICs based on flow cytometric estimates of cell size and granularity and on light-microscopic colocalization of intracellular lipid and Hoechst-positive apoptotic bodies. Cell proliferation was compared in LICs and NLICs with both an in vitro [(3)H]thymidine incorporation assay and cell cycle analysis of propidium iodide-stained cells. Results of both assays indicated that on days 4-5, LICs proliferated more rapidly than NLICs. Tropoelastin and fibronectin mRNA expression, evaluated by RT-PCR, indicated that although tropoelastin mRNA levels did not differ, fibronectin mRNA levels were approximately ninefold greater in LICs. These results demonstrate the feasibility of a flow cytometric assay for the analysis of size, granularity, and intracellular lipid content of neonatal rat lung fibroblast subsets. Subsets differed substantially with respect to proliferative capacity, fibronectin mRNA expression, and incidence of apoptosis postseptation. Together with the observed changes in relative percentages of fibroblast subsets with age, these data suggest that the ratio of LICs to NLICs could be a critical determinant of fibroblast function during lung development.

Immunolocalization of transforming growth factor alpha and epidermal growth factor receptor in lungs of patients with cystic fibrosis

Transforming growth factor alpha (TGF-alpha) is expressed in respiratory epithelial cells and alveolar macrophages during development and following lung injury. In the present study, the presence and sites of synthesis of TGF-alpha and its receptor, the epidermal growth factor receptor (EGF-R), were assessed in lung tissue from patients with severe lung disease caused by cystic fibrosis (CF). Lung sections from 24 individuals with CF, obtained at the time of lung transplantation, were compared to lung sections from five lung donors without CF. Cellular sites of TGF-alpha, EGF-R, and cellular sites of proliferation were assessed by immunohistochemistry. All CF lung sections contained multiple cell types with detectable TGF-alpha. Compared to control sections, intensity of TGF-alpha immunostaining in macrophages, airway epithelial cells, and peribronchial submucosal cells was increased. EGF-R was detected in respiratory epithelial and peribronchial stromal cells but not in alveolar macrophages. The intensity of EGF-R staining in CF lung tissue did not differ from that of controls. An increased number of cells expressing Ki-67 nuclear antigen was detected in peribronchial submucosal cells but not bronchiolar epithelial cells in the CF lungs. The increased expression of TGF-alpha in CF lung tissue supports the concept that TGF-alpha plays a role in paracrine/autocrine regulation of lung remodeling associated with injury and repair in the lungs of individuals with cystic fibrosis.

Ozone-induced acute lung injury: genetic analysis of F(2) mice generated from A/J and C57BL/6J strains

Acute lung injury (or acute respiratory distress syndrome) is a devastating and often lethal condition. This complex disease (trait) may be associated with numerous candidate genes. To discern the major gene(s) controlling mortality from acute lung injury, two inbred mouse strains displaying contrasting survival times to 10 parts/million ozone were identified. A/J (A) mice were sensitive [6.6 +/- 1 (SE) h] and C57BL/6J (B) were resistant (20.6 +/- 1 h). The designation for these phenotypes was 13 h, a point that clearly separated their survival time distributions. Our prior segregation studies suggested that survival time to ozone-induced acute lung injury was a quantitative trait, and genetic analysis identified three linked loci [acute lung injury-1, -2, and -3 (Ali1-3, respectively)]. In this report, acute lung injury in A or B mice was characterized histologically and by measuring lung wet-to-dry weight ratios at death. Ozone produced comparable effects in both strains. To further delineate genetic loci associated with reduced survival, a genomewide scan was performed with F(2) mice generated from the A and B strains. The results strengthen and extend our initial findings and firmly establish that Ali1 on mouse chromosome 11 has significant linkage to this phenotype. Ali3 was suggestive of linkage, supporting previous recombinant inbred analysis, whereas Ali2 showed no linkage. Together, our findings support the fact that several genes, including Ali1 and Ali3, control susceptibility to death after acute lung injury. Identification of these loci should allow a more focused effort to determine the key events leading to mortality after oxidant-induced acute lung injury.

Transforming growth factor-alpha deficiency reduces pulmonary fibrosis in transgenic mice

Despite evidence that implicates transforming growth factor-alpha (TGF-alpha) in the pathogenesis of acute lung injury, the contribution of TGF-alpha to the fibroproliferative response is unknown. To determine whether the development of pulmonary fibrosis depends on TGF-alpha, we induced lung injury with bleomycin in TGF-alpha null-mutation transgenic mice and wild-type mice. Lung hydroxyproline content was 1.3, 1.2, and 1.6 times greater in wild-genotype mice than in TGF-alpha-deficient animals at Days 10, 21, and 28, respectively, after a single intratracheal injection of bleomycin. At Days 7 and 10 after bleomycin treatment, lung total RNA content was 1.5 times greater in wild-genotype mice than in TGF-alpha-deficient animals. There was no significant difference between mice of the two genotypes in lung total DNA content or nuclear labeling indices after bleomycin administration. Wild-genotype mice had significantly higher lung fibrosis scores at Days 7 and 14 after bleomycin treatment than did TGF-alpha-deficient animals. There was no significant difference between TGF-alpha-deficient mice and wild-genotype mice in lung inflammation scores after bleomycin administration. To determine whether expression of other members of the epidermal growth factor (EGF) family is increased after bleomycin-induced injury, we measured lung EGF and heparin-binding- epidermal growth factor (HB-EGF) mRNA levels. Steady-state HB-EGF mRNA levels were 321% and 478% of control values in bleomycin-treated lungs at Days 7 and 10, respectively, but were not significantly different in TGF-alpha-deficient and in wild-genotype mice. EGF mRNA was not detected in normal or bleomycin-treated lungs of mice of either genotype. These results show that TGF-alpha contributes significantly to the pathogenesis of pulmonary fibrosis after bleomycin-induced injury, and that compensatory increases in other EGF family members do not occur in TGF-alpha-deficient mice.

Elevated transforming growth factor-alpha levels in bronchoalveolar lavage fluid of patients with acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) frequently results in a fibroproliferative response that precludes effective alveolar repair. Transforming growth factor-alpha (TGF-alpha), a potent epithelial and mesenchymal cell mitogen, may modulate the response to lung injury. In this study, we determined whether bronchoalveolar lavage fluid (BALF) concentrations of TGF-alpha are increased during the first 2 wk after the onset of ARDS and, if so, whether increased TGF-alpha levels in lavage fluid are associated with increased levels of procollagen peptide III (PCP III), a biological marker of fibroproliferation, and with increased fatality rates. We enrolled 74 consecutive patients with ARDS prospectively identified on admission to the intensive care unit of a tertiary care hospital, and 11 patients with chronic interstitial lung disease. Thirteen healthy volunteers served as control subjects. TGF-alpha concentrations were measured in BALF recovered on Days 3, 7, and 14 after the onset of ARDS (total of 130 lavage samples). TGF-alpha was detected in the lavage fluid of 90% of patients with ARDS (67 of 74), and in 100% of patients with idiopathic pulmonary fibrosis (IPF) (10 of 10), but in none of 13 normal volunteers. At each day tested, the median lavage TGF-alpha level of patients with ARDS was significantly higher than that of normals. The overall fatality rate was 45% (33 of 74 patients). In a univariate analysis, the median TGF-alpha levels in nonsurvivors were 1.5-fold higher at Day 7 (p = 0.06) and 1.8-fold higher at Day 14 (p = 0.048). The fatality rate was 4 times higher (CI 1.6, 17.5) for patients with both increased lavage TGF-alpha and PCP III concentrations at Day 7 than for patients with low TGF-alpha and PCP III values, indicating a synergistic relationship between TGF-alpha and PCP III. We conclude that increased levels of TGF-alpha in BALF are common in patients with ARDS and that lavage TGF-alpha is associated with a marker of the fibroproliferative response in sustained ARDS.

H441 pulmonary epithelial cell mitogenic effects and signaling pathways in response to HGF and TGF-alpha

Pulmonary epithelial cells are important in lung growth, development, and injury. H441 pulmonary adenocarcinoma cells may be a useful model for studying pulmonary epithelial cell growth factor responses in vitro. Isolated pulmonary epithelial type II cells proliferate in response to transforming growth factor (TGF)-alpha via the epidermal growth factor (EGF) receptor. Type II cells also proliferate in response to hepatocyte growth factor (HGF). In the present study, H441 cell responses to these growth factors were examined, and compared to type II cells. Both the EGF-R and the c-met proto-oncogene receptor, to which HGF binds, were immunoprecipitated from H441 cells. In H441 cells, addition of TGF-alpha resulted in phosphorylation of the EGF receptor and increased cell number and tritiated thymidine incorporation. Incubation with HGF resulted in phosphorylation of its c-met proto-oncogene receptor in type II and H441 cells, and also increased cell number and tritiated thymidine incorporation. Both HGF and TGF-alpha stimulated phosphorylation of the intracellular signaling molecules p42 and p44 mitogen activated protein kinases in H441 cells. H441 cells exhibited responses to mitogenic growth factors similar to type II cells and may be useful as a model for type II cell growth factor responses and signal transduction.

Mastitis increases growth factor messenger ribonucleic acid in bovine mammary glands

Multiparous Holstein cows were infected in two quarters by intramammary infusion with Streptococcus agalactiae and slaughtered approximately 36 h later. Mammary tissue was removed from the infected quarters, uninfected contralateral quarters, and from pair-slaughtered uninfected controls; the tissue was frozen in liquid nitrogen. The RNA was extracted, and Northern blot analysis was performed for a variety of growth factors, stress-induced genes, milk protein genes, and control genes. Infection increased levels of mRNA coding for heat shock proteins 89 alpha, 89 beta, 70, 60, and 27. Simultaneously, concentrations of alpha-lactalbumin and casein mRNA decreased; alpha-lactalbumin mRNA showed a greater decline. The mRNA for several growth factors, including acidic fibroblast growth factor, basic fibroblast growth factor, epidermal growth factor, transforming growth factor-alpha, IGF-I, and IGF-II, were also increased as was the apoptosis marker, testosterone-repressed prostate mucin-2. Concentrations of mRNA for controls, beta-actin, and glyceraldehyde-3-phosphate dehydrogenase were unaffected. These results indicate that mastitis induces changes in the levels of mRNA encoding for a variety of peptide growth factors. Such changes in growth factors could be important in a variety of processes that occur during infection, such as protection against injury or tissue repair and recovery processes.

Human Monocytes and Neutrophils Store Transforming Growth Factor-α in a Subpopulation of Cytoplasmic Granules

Transforming growth factor-α (TGF-α) exerts several effects on target cells, such as neovascularization promotion and mitogenic signalling. Using immunoelectron microscopy, we show that monocytes and neutrophils, store TGF-α in cytoplasmic granules. In monocytes, TGF-α did not colocalize with components of peroxidase-positive granules or with albumin of secretory vesicles. Furthermore, no colocalization of TGF-α with components of azurophilic or specific granules or secretory vesicles was observed in neutrophils. Activated monocytes and tissue-macrophages contained much less TGF-α–positive granules, suggesting TGF-α release. Western blot analysis showed a protein of 10 kD in lysates of monocytes. TGF-α mRNA was detected in monocytoid cells from the bone marrow by in situ hybridization. This study shows for the first time that monocytes and neutrophils contain TGF-α in all stages of maturation and that TGF-α in monocytes is stored in a large population of peroxidase-negative granules suggesting a function for these granules. Monocytes and neutrophils are important effector cells in inflammatory reactions. The present finding that these cells contain TGF-α might explain complications such as fibrosis and neoplastic transformation, caused by chronic inflammation.

Human Monocytes and Neutrophils Store Transforming Growth Factor-α in a Subpopulation of Cytoplasmic Granules

Transforming growth factor-α (TGF-α) exerts several effects on target cells, such as neovascularization promotion and mitogenic signalling. Using immunoelectron microscopy, we show that monocytes and neutrophils, store TGF-α in cytoplasmic granules. In monocytes, TGF-α did not colocalize with components of peroxidase-positive granules or with albumin of secretory vesicles. Furthermore, no colocalization of TGF-α with components of azurophilic or specific granules or secretory vesicles was observed in neutrophils. Activated monocytes and tissue-macrophages contained much less TGF-α–positive granules, suggesting TGF-α release. Western blot analysis showed a protein of 10 kD in lysates of monocytes. TGF-α mRNA was detected in monocytoid cells from the bone marrow by in situ hybridization. This study shows for the first time that monocytes and neutrophils contain TGF-α in all stages of maturation and that TGF-α in monocytes is stored in a large population of peroxidase-negative granules suggesting a function for these granules. Monocytes and neutrophils are important effector cells in inflammatory reactions. The present finding that these cells contain TGF-α might explain complications such as fibrosis and neoplastic transformation, caused by chronic inflammation.

Soluble transforming growth factor-alpha is present in the pulmonary edema fluid of patients with acute lung injury

Recent in vivo and in vitro experimental evidence indicates that transforming growth factor-alpha (TGF-alpha) is an important growth factor in the process of recovery and remodeling that occurs after acute lung injury. However, there are very little clinical data on TGF-alpha in patients with acute lung injury. Therefore, the purpose of this study was to determine if TGF-alpha is present in biologically significant concentrations in the pulmonary edema fluid from patients with acute lung injury, and to determine if the presence of TGF-alpha is specific for acute lung injury by including control patients with hydrostatic edema. Using an enzyme-linked immunosorbent assay, plasma and pulmonary edema fluid TGF-alpha levels were measured in 43 patients (34 with increased permeability edema, nine with hydrostatic edema). TGF-alpha was detected in 24 of 34 patients (71%) with increased permeability pulmonary edema (range, 0.035 to 2.57 ng/mL) compared with only two of nine patients with hydrostatic edema (p < 0.05). TGF-alpha was not detected in any plasma samples. These concentrations of TGF-alpha in pulmonary edema fluid have potent in vivo and in vitro effects on alveolar epithelial sodium transport and alveolar epithelial cell motility. In conclusion, biologically relevant concentrations of soluble TGF-alpha are present in the pulmonary edema fluid on day 1 of patients with acute lung injury, a remarkable finding with important implications for the repair and resolution of acute lung injury, particularly since TGF-alpha was detected so early in the course of acute lung injury.

Epidermal growth factor inhibits Ca(2+)-dependent Cl- transport in T84 human colonic epithelial cells

This study examined whether epidermal growth factor (EGF) inhibits Ca(2+)-dependent Cl- secretion by T84 cells. Basolateral EGF inhibited Cl- secretion induced by carbachol or thapsigargin, without blocking the rise in intracellular Ca2+. Studies have shown that carbachol renders T84 cells refractory to subsequent stimulation by thapsigargin, an effect ascribed to D-myo-inositol 3,4,5,6-tetrakisphosphate [D-Ins(3,4,5,6)P4]. EGF also increased DL-Ins(3,4,5,6)P4 to a maximum of 170% above control. However, despite the fact that EGF inhibited Cl- secretion at 1 min, DL-Ins(3,4,5,6)P4 was not elevated at this time point. EGF plus carbachol had a greater inhibitory effect on Cl- secretion than either alone, indicating the likely involvement of an additional inhibitory pathway activated by EGF. Staurosporine did not alter the ability of EGF to inhibit Cl- secretion or increase DL-Ins(3,4,5,6)P4. In contrast, genistein inhibited the rise in DL-Ins(3,4,5,6)P4 and partially reversed EGF's inhibitory effect on Cl- secretion. In conclusion, EGF and carbachol can both inhibit Cl- secretion via D-Ins(3,4,5,6)P4, whereas EGF also generates an additional inhibitory signal.