TGF-beta1 stimulates IL-8 release, COX-2 expression, and PGE(2) release in human airway smooth muscle cells

Losartan Treatment Reduces Esophageal Eosinophilic Inflammation in a Subset of Eosinophilic Esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic, food antigen-driven esophageal disorder. Connective tissue disorders (CTDs) and esophageal connective tissue alterations are associated with EoE. Therefore, angiotensin II type 1 receptor blockade with losartan, an accepted CTD treatment, is a potential EoE treatment.

OBJECTIVE

We evaluated losartan's effects on esophageal pathology, symptoms, and safety in patients with EoE with and without a CTD in an open-label, non-placebo controlled multisite study.

METHODS

Fifteen participants with EoE, aged 5 to 23 years, underwent treatment with per-protocol titrated doses of losartan in an open-label, 16-week pilot trial. Losartan was added to standard of care therapy and 14 patients completed the study. Eosinophil counts served as the primary end point, whereas we also assessed the EoE Histology Scoring System, Endoscopic Reference Scores, EoE Diagnostic Panel, and patient-reported outcomes.

RESULTS

Esophageal eosinophilia was not reduced after losartan. The peak eosinophil count was not reduced for the proximal (median [interquartile range]: -3 [-22 to 3]; P = .49) and distal esophagus (median [interquartile range]: -18 [-39 to -1]; P = .23). There were no differences in losartan response in EoE with or without CTD (n = 7 and 8, respectively). Regardless, in a small subset of four participants esophageal eosinophilia was resolved with a concomitant reduction in EoE Histology Scoring System score and Endoscopic Reference Score. Across all subjects, the Pediatric EoE Symptom Score, Pediatric Quality of Life Inventory EoE Module, and EoE Diagnostic Panel improved after losartan (P < .05).

CONCLUSIONS

Losartan treatment was associated with improved patient-reported outcome scores and EoE Diagnostic Panel biomarkers although without a reduction in esophageal eosinophilia overall. A subset of patients demonstrated improved histopathologic and endoscopic features that could not be tied to a specific feature predicting response to treatment.

Respiratory issues in patients with multiple sclerosis as a risk factor during SARS-CoV-2 infection: a potential role for exercise

Coronavirus disease-2019 (COVID-19) is associated with cytokine storm and is characterized by acute respiratory distress syndrome (ARDS) and pneumonia problems. The respiratory system is a place of inappropriate activation of the immune system in people with multiple sclerosis (MS), and this may cause damage to the lung and worsen both MS and infections.The concerns for patients with multiple sclerosis are because of an enhance risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The MS patients pose challenges in this pandemic situation, because of the regulatory defect of autoreactivity of the immune system and neurological and respiratory tract symptoms. In this review, we first indicate respiratory issues associated with both diseases. Then, the main mechanisms inducing lung damages and also impairing the respiratory muscles in individuals with both diseases is discussed. At the end, the leading role of physical exercise on mitigating respiratory issues inducing mechanisms is meticulously evaluated.

Development of Adaptive Immunity and Its Role in Lung Remodeling

Asthma is characterized by airflow limitations resulting from bronchial closure, which can be either reversible or fixed due to changes in airway tissue composition and structure, also known as remodeling. Airway remodeling is defined as increased presence of mucins-producing epithelial cells, increased thickness of airway smooth muscle cells, angiogenesis, increased number and activation state of fibroblasts, and extracellular matrix (ECM) deposition. Airway inflammation is believed to be the main cause of the development of airway remodeling in asthma. In this chapter, we will review the development of the adaptive immune response and the impact of its mediators and cells on the elements defining airway remodeling in asthma.

The Genetic Factors of the Airway Epithelium Associated with the Pathology of Asthma

Asthma is a chronic disease of the airways characterized by inflammation, tightened muscles, and thickened airway walls leading to symptoms such as shortness of breath, chest tightness, and cough in patients. The increased risk of asthma in children of asthmatics parents supports the existence of genetic factors involved in the pathogenesis of this disease. Genome-wide association studies have discovered several single nucleotide polymorphisms associated with asthma. These polymorphisms occur within several genes and can contribute to different asthma phenotypes, affect disease severity, and clinical response to different therapies. The complexity in the etiology of asthma also results from interactions between environmental and genetic factors. Environmental exposures have been shown to increase the prevalence of asthma in individuals who are genetically susceptible. This review summarizes what is currently known about the genetics of asthma in relation to risk, response to common treatments, and gene-environmental interactions.

The CFTR Amplifier Nesolicaftor Rescues TGF-β1 Inhibition of Modulator-Corrected F508del CFTR Function

Highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulators have led to dramatic improvements in lung function in many people with cystic fibrosis (PwCF). However, the efficacy of CFTR modulators may be hindered by persistent airway inflammation. The cytokine transforming growth factor-beta1 (TGF-β1) is associated with worse pulmonary disease in PwCF and can diminish modulator efficacy. Thus, strategies to augment the CFTR response to modulators in an inflammatory environment are needed. Here, we tested whether the CFTR amplifier nesolicaftor (or PTI-428) could rescue the effects of TGF-β1 on CFTR function and ciliary beating in primary human CF bronchial epithelial (CFBE) cells. CFBE cells homozygous for F508del were treated with the combination of elexacaftor/tezacaftor/ivacaftor (ETI) and TGF-β1 in the presence and absence of nesolicaftor. Nesolicaftor augmented the F508del CFTR response to ETI and reversed TGF-β1-induced reductions in CFTR conductance by increasing the expression of CFTR mRNA. Nesolicaftor further rescued the reduced ciliary beating and increased expression of the cytokines IL-6 and IL-8 caused by TGF-β1. Finally, nesolicaftor augmented the F508del CFTR response to ETI in CFBE cells overexpressing miR-145, a negative regulator of CFTR expression. Thus, CFTR amplifiers, but only when used with highly effective modulators, may provide benefit in an inflamed environment.

Differences in Inflammatory Cytokine Profile in Obesity-Associated Asthma: Effects of Weight Loss

Obesity and asthma are associated with systemic inflammation maintained by mediators released by adipose tissue and lung. This study investigated the inflammatory serum mediator profile in obese subjects (O) (n = 35), non-obese asthma (NOA) patients (n = 14), obese asthmatics (OA) (n = 21) and healthy controls (HC) (n = 33). The effect of weight loss after bariatric surgery (BS) was examined in 10 OA and 31 O subjects. We analyzed serum markers including leptin, adiponectin, TGF-β1, TNFR2, MCP-1, ezrin, YKL-40, ST2, IL-5, IL-9, and IL-18. Compared with HC subjects, the O group showed increased levels of leptin, TGF-β1, TNFR2, MCP-1, ezrin, YKL-40, and ST2; the OA group presented increased levels of MCP-1, ezrin, YKL-40, and IL-18, and the NOA group had increased levels of ezrin, YKL-40, IL-5, and IL-18. The higher adiponectin/leptin ratio in NOA with respect to OA subjects was the only significant difference between the two groups. IL-9 was the only cytokine with significantly higher levels in OA with respect to O subjects. TNFR2, ezrin, MCP-1, and IL-18 concentrations significantly decreased in O subjects after BS. O, OA, and NOA showed distinct patterns of systemic inflammation. Leptin and adiponectin are regulated in asthma by obesity-dependent and -independent mechanisms. Combination of asthma and obesity does not result in significant additive effects on circulating cytokine levels.

Losartan ameliorates TGF-β1-induced CFTR dysfunction and improves correction by cystic fibrosis modulator therapies

Highly effective modulator therapies dramatically improve the prognosis for those with cystic fibrosis (CF). The triple combination of elexacaftor, tezacaftor, and ivacaftor (ETI) benefits many, but not all, of those with the most common F508del mutation in the CF transmembrane conductance regulator (CFTR). Here, we showed that poor sweat chloride concentration responses and lung function improvements upon initiation of ETI were associated with elevated levels of active TGF-β1 in the upper airway. Furthermore, TGF-β1 impaired the function of ETI-corrected F508del-CFTR, thereby increasing airway surface liquid (ASL) absorption rates and inducing mucus hyperconcentration in primary CF bronchial epithelial cells in vitro. TGF-β1 not only decreased CFTR mRNA, but was also associated with increases in the mRNA expression of TNFA and COX2 and TNF-α protein. Losartan improved TGF-β1-mediated inhibition of ETI-corrected F508del-CFTR function and reduced TNFA and COX2 mRNA and TNF-α protein expression. This likely occurred by improving correction of mutant CFTR rather than increasing its mRNA (without an effect on potentiation), thereby reversing the negative effects of TGF-β1 and improving ASL hydration in the CF airway epithelium in vitro. Importantly, these effects were independent of type 1 angiotensin II receptor inhibition.

Inhibition of TGF-β Signaling Attenuates Disuse-induced Trabecular Bone Loss After Spinal Cord Injury in Male Mice

Bone loss is one of the most common complications of immobilization after spinal cord injury (SCI). Whether transforming growth factor (TGF)-β signaling plays a role in SCI-induced disuse bone loss has not been determined. Thus, 16-week-old male mice underwent sham or spinal cord contusion injury to cause complete hindlimb paralysis. Five days later, 10 mg/kg/day control (IgG) or anti-TGF-β1,2,3 neutralizing antibody (1D11) was administered twice weekly for 4 weeks. Femurs were examined by micro-computed tomography (micro-CT) scanning and histology. Bone marrow (BM) supernatants were analyzed by enzyme-linked immunosorbent assay for levels of procollagen type 1 intact N-terminal propeptide (P1NP), tartrate-resistant acid phosphatase (TRAcP-5b), receptor activator of nuclear factor-kappa B ligand (RANKL), osteoprotegerin (OPG), and prostaglandin E2 (PGE2). Distal femoral micro-CT analysis showed that SCI-1D11 mice had significantly (P < .05) attenuated loss of trabecular fractional bone volume (123% SCI-1D11 vs 69% SCI-IgG), thickness (98% vs 81%), and connectivity (112% vs 69%) and improved the structure model index (2.1 vs 2.7). Histomorphometry analysis revealed that osteoclast numbers were lower in the SCI-IgG mice than in sham-IgG control. Biochemically, SCI-IgG mice had higher levels of P1NP and PGE2 but similar TRAcP-5b and RANKL/OPG ratio to the sham-IgG group. The SCI-1D11 group exhibited higher levels of P1NP but similar TRAcP-5b, RANKL/OPG ratio, and PGE2 to the sham-1D11 group. Furthermore, 1D11 treatment prevented SCI-induced hyperphosphorylation of tau protein in osteocytes, an event that destabilizes the cytoskeleton. Together, inhibition of TGF-β signaling after SCI protects trabecular bone integrity, likely by balancing bone remodeling, inhibiting PGE2 elevation, and preserving the osteocyte cytoskeleton.

Gene transcripts expressed in equine white blood cells are potential biomarkers of extracorporeal shock wave therapy

Extracorporeal shockwave therapy (ESWT) is a treatment applied to musculoskeletal injuries in equine athletes to alleviate pain and accelerate healing. ESWT also causes acute tissue damage. Therefore, its ability to act as an analgesic and cause tissue damage potentially increases the risk of a catastrophic event if used shortly before a strenuous competition such as horseracing. While ESWT is prohibited by many racing jurisdictions within 10 days prior to competition, a test to detect whether a horse has received ESWT is needed. ESWT changes the protein levels of inflammatory mediators in blood, and white blood cells (WBC) typically produce these proteins. Changes in gene expression precede changes in protein production; thus, it was hypothesized that WBC gene transcripts might serve as biomarkers of ESWT. To test this hypothesis, six thoroughbred horses received a single administration of ESWT to the distal limb, and WBC RNA was extracted from blood samples collected before (0 h) and after ESWT (2, 4, 6, 24, 48, and 72 h). Targeted and untargeted analyses evaluated the transcriptome using quantitative PCR (qPCR) and microarray. The expression of IL-1α, IL-1β, TNF-α, IL-1Ra1, IL-1Ra2 and TGF-β1, and BMPR1A in circulating WBCs was significantly up-regulated, while IFN-γ, ZNF483, TMEM80, CAH6, ENPP, and S8723 were significantly down-regulated at various time points following ESWT. These data support the hypothesis that changes in WBC gene transcripts could serve as biomarkers for ESWT.

TGF-β: The missing link in obesity-associated airway diseases?

Obesity is emerging as a global public health epidemic. The co-morbidities associated with obesity significantly contribute to reduced quality of life, mortality, and global healthcare burden. Compared to other asthma comorbidities, obesity prominently engenders susceptibility to inflammatory airway diseases such as asthma and chronic obstructive pulmonary disease (COPD), contributes to greater disease severity and evokes insensitivity to current therapies. Unlike in other metabolic diseases associated with obesity, the mechanistic link between obesity and airway diseases is only poorly defined. Transforming growth factor-β (TGF-β) is a pleiotropic inflammatory cytokine belonging to a family of growth factors with pivotal roles in asthma. In this review, we summarize the role of TGF-β in major obesity-associated co-morbidities to shed light on mechanisms of the diseases. Literature evidence shows that TGF-β mechanistically links many co-morbidities with obesity through its profibrotic, remodeling, and proinflammatory functions. We posit that TGF-β plays a similar mechanistic role in obesity-associated inflammatory airway diseases such as asthma and COPD. Concerning the role of TGF-β on metabolic effects of obesity, we posit that TGF-β has a similar mechanistic role in obesity-associated inflammatory airway diseases in interplay with different comorbidities such as hypertension, metabolic diseases like type 2 diabetes, and cardiomyopathies. Future studies in TGF-β-dependent mechanisms in obesity-associated inflammatory airway diseases will advance our understanding of obesity-induced asthma and help find novel therapeutic targets for prevention and treatment.

Transforming Growth Factor-β1 Decreases β2-Agonist-induced Relaxation in Human Airway Smooth Muscle

Helper T effector cytokines implicated in asthma modulate the contractility of human airway smooth muscle (HASM) cells. We have reported recently that a profibrotic cytokine, transforming growth factor (TGF)-β1, induces HASM cell shortening and airway hyperresponsiveness. Here, we assessed whether TGF-β1 affects the ability of HASM cells to relax in response to β₂-agonists, a mainstay treatment for airway hyperresponsiveness in asthma. Overnight TGF-β1 treatment significantly impaired isoproterenol (ISO)-induced relaxation of carbachol-stimulated, isolated HASM cells. This single-cell mechanical hyporesponsiveness to ISO was corroborated by sustained increases in myosin light chain phosphorylation. In TGF-β1-treated HASM cells, ISO evoked markedly lower levels of intracellular cAMP. These attenuated cAMP levels were, in turn, restored with pharmacological and siRNA inhibition of phosphodiesterase 4 and Smad3, respectively. Most strikingly, TGF-β1 selectively induced phosphodiesterase 4D gene expression in HASM cells in a Smad2/3-dependent manner. Together, these data suggest that TGF-β1 decreases HASM cell β₂-agonist relaxation responses by modulating intracellular cAMP levels via a Smad2/3-dependent mechanism. Our findings further define the mechanisms underlying β₂-agonist hyporesponsiveness in asthma, and suggest TGF-β1 as a potential therapeutic target to decrease asthma exacerbations in severe and treatment-resistant asthma.

Tetrandrine Ameliorates Airway Remodeling of Chronic Asthma by Interfering TGF-β1/Nrf-2/HO-1 Signaling Pathway-Mediated Oxidative Stress

Background

Imbalanced oxidative stress and antioxidant defense are involved in airway remodeling in asthma. It has been demonstrated that Tetrandrine has a potent role in antioxidant defense in rheumatoid arthritis and hypertension. However, the correlation between Tetrandrine and oxidative stress in asthma is utterly blurry. This study aimed to investigate the role of Tetrandrine on oxidative stress-mediated airway remolding.

Materials and Methods

Chronic asthma was established by ovalbumin (OVA) administration in male Wistar rats. Histopathology was determined by HE staining. Immunofluorescence was employed to detect the expression of α-SMA and Nrf-2. Level of oxidative stress and matrix metalloproteinases were examined by ELISA kits. Cell viability and cell cycle of primary airway smooth muscle cells (ASMCs) were evaluated by CCK8 and flow cytometry, respectively. Signal molecules were detected using western blot.

Results

Tetrandrine effectively impairs OVA-induced airway inflammatory and airway remodeling by inhibiting the expression of CysLT1 and CysLTR1. The increase of oxidative stress and subsequent enhancement of MMP9 and TGF-β1 expression were rescued by the administration of Tetrandrine in the rat model of asthma. In in vitro experiments, Tetrandrine markedly suppressed TGF-β1-evoked cell viability and cell cycle promotion of ASMCs in a dose-dependent manner. Furthermore, Tetrandrine promoted Nrf-2 nuclear transcription and activated its downstream HO-1 in vivo and in vitro.

Conclusion

Tetrandrine attenuates airway inflammatory and airway remodeling in rat model of asthma and TGF-β1-induced cell proliferation of ASMCs by regulating oxidative stress in primary ASMCs, suggesting that Tetrandrine possibly is an effective candidate therapy for asthma.

Protocatechuic acid inhibits TGF-β1-induced proliferation and migration of human airway smooth muscle cells

Protocatechuic acid (3, 4-dihydroxybenzoic acid, PCA) is a major metabolite of anthocyanins and was reported to possess anti-allergic response. However, the effects of PCA on airway smooth muscle cells (ASMCs) proliferation and migration remain unclear. Therefore, this study aims to investigate the effects of PCA on proliferation and migration of ASMCs. ASMCs were pre-incubated with various concentrations of PCA for 30 min before stimulation with transforming growth factor-β1 (TGF-β1) for different times. Cell proliferation was determined using the colony formation assay. Cell migration was detected using the Transwell chamber assay. The levels of type I collagen, fibronectin, phosphorylated Smad2, Smad2, phosphorylated Smad3 and Smad3 were detected by western blot analysis. Our results demonstrated that PCA inhibited the proliferation and migration of ASMCs, as well as suppressed the expression levels of type I collagen and fibronectin in ASMCs induced by TGF-β1. Furthermore, PCA obviously down-regulated the phosphorylation levels of Smad2/3 in ASMCs exposed to TGF-β1. Taken together, the present results have revealed that PCA inhibits asthma airway remodeling by suppressing proliferation and extracellular matrix (ECM) protein deposition in TGF-β1-mediated ASMCs via the inactivation of Smad2/3 signaling pathway. Therefore, PCA may be useful for the prevention or treatment of asthma airway remodeling.

Safer approaches to therapeutic modulation of TGF-β signaling for respiratory disease

The transforming growth factor (TGF)-β cytokines play a central role in development and progression of chronic respiratory diseases. TGF-β overexpression in chronic inflammation, remodeling, fibrotic process and susceptibility to viral infection is established in the most prevalent chronic respiratory diseases including asthma, COPD, lung cancer and idiopathic pulmonary fibrosis. Despite the overwhelming burden of respiratory diseases in the world, new pharmacological therapies have been limited in impact. Although TGF-β inhibition as a therapeutic strategy carries great expectations, the constraints in avoiding compromising the beneficial pleiotropic effects of TGF-β, including the anti-proliferative and immune suppressive effects, have limited the development of effective pharmacological modulators. In this review, we focus on the pathways subserving deleterious and beneficial TGF-β effects to identify strategies for selective modulation of more distal signaling pathways that may result in agents with improved safety/efficacy profiles. Adverse effects of TGF-β inhibitors in respiratory clinical trials are comprehensively reviewed, including those of the marketed TGF-β modulators, pirfenidone and nintedanib. Precise modulation of TGF-β signaling may result in new safer therapies for chronic respiratory diseases.

Transforming Growth Factor β1 Function in Airway Remodeling and Hyperresponsiveness. The Missing Link?

The pathogenesis of asthma includes a complex interplay among airway inflammation, hyperresponsiveness, and remodeling. Current evidence suggests that airway structural cells, including bronchial smooth muscle cells, myofibroblasts, fibroblasts, and epithelial cells, mediate all three aspects of asthma pathogenesis. Although studies show a connection between airway remodeling and changes in bronchomotor tone, the relationship between the two remains unclear. Transforming growth factor β1 (TGF-β1), a growth factor elevated in the airway of patients with asthma, plays a role in airway remodeling and in the shortening of various airway structural cells. However, the role of TGF-β1 in mediating airway hyperresponsiveness remains unclear. In this review, we summarize the literature addressing the role of TGF-β1 in airway remodeling and shortening. Through our review, we aim to further elucidate the role of TGF-β1 in asthma pathogenesis and the link between airway remodeling and airway hyperresponsiveness in asthma and to define TGF-β1 as a potential therapeutic target for reducing asthma morbidity and mortality.

Airway remodeling associated with cough hypersensitivity as a consequence of persistent cough: An experimental study

BACKGROUND

Chronic cough involves airway remodeling associated with cough reflex hypersensitivity. Whether cough itself induces these features remains unknown.

METHODS

Guinea pigs were assigned to receive treatment with citric acid (CA), saline (SA), or CA+dextromethorphan (DEX). All animals were exposed to 0.5M CA on days 1 and 22. On days 4-20, the CA and CA+DEX groups were exposed to CA, and the SA group to saline thrice weekly, during which the CA+DEX group was administered DEX pretreatment to inhibit cough. The number of coughs was counted during each 10-min CA or SA exposure. Terbutaline premedication was started to prevent bronchoconstriction. Bronchoalveolar lavage and pathology were examined on day 25. Average cough number for 10 CA exposures was examined as "cough index" in the CA group, which was divided into frequent (cough index>5) and infrequent (<5) cough subgroups for lavage and pathology analysis.

RESULTS

The number of coughs significantly increased in the CA group from day 13 onwards. In the CA+DEX and SA groups, the number of coughs did not differ between days 1 and 22, while average number of coughs during days 4-20 was significantly lower than at days 1 and 22. Bronchoalveolar cell profiles were similar among the four groups. The smooth muscle area of small airways was significantly greater in the frequent-cough subgroup than in the other groups (in which it was similar), and highly correlated with cough index in CA group.

CONCLUSION

Repeated cough induces airway smooth muscle remodeling associated with cough reflex hypersensitivity.

Opposing roles of TGF-β in prostaglandin production by human follicular dendritic cell-like cells

Prostaglandins (PGs) are recognized as important immune regulators. Using human follicular dendritic cell (FDC)-like HK cells, we have investigated the immunoregulatory role of PGs and their production mechanisms. The present study was aimed at determining the role of TGF-β in IL-1β-induced cyclooxygenase-2 (COX-2) expression by immunoblotting. COX-2 is the key enzyme responsible for PG production in HK cells. TGF-β, when added simultaneously with IL-1β, gave rise to an additive effect on COX-2 expression in a dose-dependent manner. However, TGF-β inhibited IL-1β-stimulated COX-2 expression when it was added at least 12h before IL-1β addition. The inhibitory effect of TGF-β was specific to IL-1β-induced COX-2 expression in HK cells. The stimulating and inhibitory effects of TGF-β were reproduced in IL-1β-stimulated PG production. Based on our previous results of the essential requirement of ERK and p38 MAPKs in TGF-β-induced COX-2 expression, we examined whether the differential activation of these MAPKs would underlie the opposing activities of TGF-β. The phosphorylation of ERK and p38 MAPKs was indeed enhanced or suppressed by the simultaneous treatment or pre-treatment, respectively. These results suggest that TGF-β exerts opposing effects on IL-1β-induced COX-2 expression in HK cells by differentially regulating activation of ERK and p38 MAPKs.

Human respiratory syncytial virus non-structural protein NS1 modifies miR-24 expression via transforming growth factor-β

Human respiratory syncytial virus (RSV) is a major health challenge in the young and elderly owing to the lack of a safe and effective vaccine and proven antiviral drugs. Understanding the mechanisms by which viral genes and proteins modulate the host response to infection is critical for identifying novel disease intervention strategies. In this study, the RSV non-structural protein NS1 was shown to suppress miR-24 expression during infection. Lack of NS1 was linked to increased expression of miR-24, whilst NS1 overexpression suppressed miR-24 expression. NS1 was found to induce Kruppel-like factor 6 (KLF6), a transcription factor that positively regulates the transforming growth factor (TGF)-b pathway to induce cell cycle arrest. Silencing of KLF6 led to increased miR-24 expression via downregulation of TGF-β. Treatment with exogenous TGF-β suppressed miR-24 expression and induced KLF6. Confocal microscopy showed co-localization of KLF6 and RSV NS1. These findings indicated that RSV NS1 interacts with KLF6 and modulates miR-24 expression and TGF-β, which facilitates RSV replication.

Chronic effects of air pollution on respiratory health in Southern California children: findings from the Southern California Children's Health Study

Outdoor air pollution is one of the leading contributors to adverse respiratory health outcomes in urban areas around the world. Children are highly sensitive to the adverse effects of air pollution due to their rapidly growing lungs, incomplete immune and metabolic functions, patterns of ventilation and high levels of outdoor activity. The Children's Health Study (CHS) is a continuing series of longitudinal studies that first began in 1993 and has focused on demonstrating the chronic impacts of air pollution on respiratory illnesses from early childhood through adolescence. A large body of evidence from the CHS has documented that exposures to both regional ambient air and traffic-related pollutants are associated with increased asthma prevalence, new-onset asthma, risk of bronchitis and wheezing, deficits of lung function growth, and airway inflammation. These associations may be modulated by key genes involved in oxidative-nitrosative stress pathways via gene-environment interactions. Despite successful efforts to reduce pollution over the past 40 years, air pollution at the current levels still brings many challenges to public health. To further ameliorate adverse health effects attributable to air pollution, many more toxic pollutants may require regulation and control of motor vehicle emissions and other combustion sources may need to be strengthened. Individual interventions based on personal susceptibility may be needed to protect children's health while control measures are being implemented.

Potency of non-steroidal anti-inflammatory drugs in chemotherapy

Cancer cell resistance, particularly multidrug resistance (MDR), is the leading cause of chemotherapy failure. A number of mechanisms involved in the development of MDR have been described, including the overexpression of ATP-dependent membrane-bound transport proteins. The enhanced expression of these proteins, referred to as ATP-binding cassette (ABC) transporters, results in an increased cellular efflux of the cytotoxic drug, thereby reducing its intracellular concentration to an ineffective level. Non-steroidal anti-inflammatory drugs (NSAIDs) are the most frequently consumed drugs worldwide. NSAIDs are mainly used to treat pain, fever and inflammation. Numerous studies suggest that NSAIDs also show promise as anticancer drugs. NSAIDs have been shown to reduce cancer cell proliferation, motility, angiogenesis and invasiveness. In addition to these effects, NSAIDs have been shown to induce apoptosis in a wide variety of cancer types. Moreover, several studies have indicated that NSAIDs may sensitise cancer cells to the antiproliferative effects of cytotoxic drugs by modulating ABC transporter activity. Therefore, combining specific NSAIDs with chemotherapeutic drugs may have clinical applications. Such treatments may allow for the use of a lower dose of cytotoxic drugs and may also enhance the effectiveness of therapy. The objective of this review was to discuss the possible role of NSAIDs in the modulation of antitumour drug cytotoxicity. We particularly emphasised on the use of COX-2 inhibitors in combination with chemotherapy and the molecular and cellular mechanisms underlying the alterations in outcome that occur in response to this combination therapy.

Plasminogen-stimulated inflammatory cytokine production by airway smooth muscle cells is regulated by annexin A2

Plasminogen has a role in airway inflammation. Airway smooth muscle (ASM) cells cleave plasminogen into plasmin, a protease with proinflammatory activity. In this study, the effect of plasminogen on cytokine production by human ASM cells was investigated in vitro. Levels of IL-6 and IL-8 in the medium of ASM cells were increased by incubation with plasminogen (5-50 μg/ml) for 24 hours (P < 0.05; n = 6-9), corresponding to changes in the levels of cytokine mRNA at 4 hours. The effects of plasminogen were attenuated by α2-antiplasmin (1 μg/ml), a plasmin inhibitor (P < 0.05; n = 6-12). Exogenous plasmin (5-15 mU/ml) also stimulated cytokine production (P < 0.05; n = 6-8) in a manner sensitive to serine-protease inhibition by aprotinin (10 KIU/ml). Plasminogen-stimulated cytokine production was increased in cells pretreated with basic fibroblast growth factor (300 pM) in a manner associated with increases in urokinase plasminogen activator expression and plasmin formation. The knockdown of annexin A2, a component of the putative plasminogen receptor comprised of annexin A2 and S100A10, attenuated plasminogen conversion into plasmin and plasmin-stimulated cytokine production by ASM cells. Moreover, a role for annexin A2 in airway inflammation was demonstrated in annexin A2-/- mice in which antigen-induced increases in inflammatory cell number and IL-6 levels in the bronchoalveolar lavage fluid were reduced (P < 0.01; n = 10-14). In conclusion, plasminogen stimulates ASM cytokine production in a manner regulated by annexin A2. Our study shows for the first time that targeting annexin A2-mediated signaling may provide a novel therapeutic approach to the treatment of airway inflammation in diseases such as chronic asthma.

Proinflammatory conditions promote hepatocellular carcinoma onset and progression via activation of Wnt and EGFR signaling pathways

The aim of the current study was to investigate how proinflammatory conditions affect growth and progression of hepatocellular carcinoma. Human hepatoma cell lines were treated with lipopolysaccharide (LPS) or cyclooxygenase-2 inhibitor, Celecoxib, and in vitro proliferation, apoptosis, and cell cycle progression were assessed. This was followed up with in vivo xenograft assays to monitor tumor growth and metastatic progression under different treatment conditions. While LPS induced cell proliferation, Celecoxib induced apoptosis. Flow cytometry analysis demonstrated that S-phase cell count in LPS group was higher than control group (41.9 ± 3.2 vs 30.6 ± 0.1%, respectively), whereas G0/G1-phase cells were significantly higher in the Celecoxib group in comparison with the control group (69.6 ± 5.0 vs 50.4 ± 1.6%, respectively) (p < 0.05). Immunoblot analyses showed induction of epidermal growth factor receptor expression and induction and nuclear accumulation of Wnt/β-catenin and p65 in LPS group. Xenograft assays showed that LPS treatment induced comparatively large, rapidly growing tumors (2,702 ± 572 mm(3)) that metastasized to lungs, whereas Celecoxib treatment alone (1,008 ± 296 mm(3)) or in combination with LPS (1,303 ± 283 mm(3)) suppressed tumor growth in comparison to control groups (2,072 ± 456 mm(3)) (n = 5; p < 0.05). Inflammation can thus promote hepatoma cell proliferation and growth, and enhance the invasion and metastatic ability of hepatocarcinoma cells through inducing tumor angiogenesis, which in turn may be related to the activation of Wnt/β-catenin and EGFR signaling pathways.

Secreted factors from human mast cells trigger inflammatory cytokine production by human airway smooth muscle cells

BACKGROUND

A notable feature of allergic asthma is the infiltration of mast cells into smooth muscle in the human airway. Thus, mast cells and human airway smooth muscle (hASM) cells are likely to exhibit mutual functional modulation via direct cell-cell contact or through released factors. This study examined mast cell modulation of hASM cell cytokine release.

METHODS

The mast cell line HMCα was used to model mast cell function. hASM cells were either co-cultured directly with resting or IgE/antigen-stimulated HMCα cells or treated with HMCα-conditioned media to examine the impact on cytokine release. The activation pathways triggered in hASM cells by the mast cell-derived factors were examined through the use of selective inhibitors and by Western blotting.

RESULTS

HMCα cells, or their conditioned media, induced the expression of cytokines (IL-8 and IL-6) by hASM cells at both the mRNA and the protein level. Cytokine expression in hASM cells was greatly amplified when HMCα cells were IgE/antigen-activated. The effects of the conditioned media were not mediated by the chemokines MCP-1 and MIP-1α or by exosomes. While the mast cell-derived factor(s) increased p38(MAPK) phosphorylation in hASM cells, cytokine production was not inhibited by the p38(MAPK) inhibitor SB203580. hASM cell production of IL-8 induced by HMCα condition media but not IL-6 was, however, attenuated by the Src tyrosine kinase inhibitor PP2.

CONCLUSIONS

Our study shows that the release of soluble mediators by activated mast cells can stimulate hASM cells to elicit production of proinflammatory cytokines that may then exacerbate airway inflammation in asthma.

Hydrogen sulfide inhibits proliferation and release of IL-8 from human airway smooth muscle cells

Hydrogen sulfide (H(2)S) is synthesized intracellularly by the enzymes cystathionine-γ-lyase and cystathionine-β-synthase (CBS), and is proposed to be a gasotransmitter with effects in modulating inflammation and cellular proliferation. We determined a role of H(2)S in airway smooth muscle (ASM) function. ASM were removed from resection or transplant donor lungs and were placed in culture. Proliferation of ASM was induced by FCS and the proinflammatory cytokine, IL-1β. Proliferation of ASM and IL-8 release were measured by bromodeoxyuridine incorporation and ELISA, respectively. Exposure of ASM to H(2)S "donors" inhibited this proliferation and IL-8 release. Methemoglobin, a scavenger of endogenous H(2)S, increased DNA synthesis induced by FCS and IL-1β. In addition, methemoglobin increased IL-8 release induced by FCS, but not by IL-1β, indicating a role for endogenous H(2)S in these systems. Inhibition of CBS, but not cystathionine-γ-lyase, reversed the inhibitory effect of H(2)S on proliferation and IL-8 release, indicating that this is dependent on CBS. CBS mRNA and protein expression were inhibited by H(2)S donors, and were increased by methemoglobin, indicating that CBS is the main enzyme responsible for endogenous H(2)S production. Finally, we found that exogenous H(2)S inhibited the phosphorylation of extracellular signal-regulated kinase-1/2 and p38, which could represent a mechanism by which H(2)S inhibited cellular proliferation and IL-8 release. In summary, H(2)S production provides a novel mechanism for regulation of ASM proliferation and IL-8 release. Therefore, regulation of H(2)S may represent a novel approach to controlling ASM proliferation and cytokine release that is found in patients with asthma.

A20 regulation of nuclear factor-κB: perspectives for inflammatory lung disease

Persistent activation of NF-κB is central to the pathogenesis of many inflammatory lung disorders, including cystic fibrosis, asthma, and chronic obstructive pulmonary disease. A20 is an endogenous negative regulator of NF-κB signaling, which has been widely described in autoimmune and inflammatory disorders, including diabetes and Crohn's disease, but which has received little attention in terms of chronic lung disorders. This review examines the existing body of research on A20 regulation of NF-κB signaling and details the mechanism and regulation of A20 action focusing, where possible, on pulmonary inflammation. A20 and its associated signaling molecules are highlighted as being of potential therapeutic interest for the treatment of inflammatory disorders, and a proposed model of A20 activity in inflammatory lung disease is provided.

TGFβ1 induces IL-6 and inhibits IL-8 release in human bronchial epithelial cells: the role of Smad2/3

Human bronchial epithelial (HBE) cells contribute to asthmatic airway inflammation by secreting cytokines, chemokines, and growth factors, including interleukin (IL)-6, IL-8 and transforming growth factor (TGF) β1, all of which are elevated in asthmatic airways. This study examines the signaling pathways leading to TGFβ1 induced IL-6 and IL-8 in primary HBE cells from asthmatic and non-asthmatic volunteers. HBE cells were stimulated with TGFβ1 in the presence or absence of signaling inhibitors. IL-6 and IL-8 protein and mRNA were measured by ELISA and real-time PCR respectively, and cell signaling kinases by Western blot. TGFβ1 increased IL-6, but inhibited IL-8 production in both asthmatic and non-asthmatic cells; however, TGF induced significantly more IL-6 in asthmatic cells. Inhibition of JNK MAP kinase partially reduced TGFβ1 induced IL-6 in both cell groups. TGFβ1 induced Smad2 phosphorylation, and blockade of Smad2/3 prevented both the TGFβ1 modulated IL-6 increase and the decrease in IL-8 production in asthmatic and non-asthmatic cells. Inhibition of Smad2/3 also increased basal IL-8 release in asthmatic cells but not in non-asthmatic cells. Using CHIP assays we demonstrated that activated Smad2 bound to the IL-6, but not the IL-8 promoter region. We conclude that the Smad2/3 pathway is the predominant TGFβ1 signaling pathway in HBE cells, and this is altered in asthmatic bronchial epithelial cells. Understanding the mechanism of aberrant pro-inflammatory cytokine production in asthmatic airways will allow the development of alternative ways to control airway inflammation.

Eicosanoids in inflammation and cancer: the role of COX-2

Eicosanoids, a family of oxygenated metabolites of eicosapolyenoic fatty acids, such as arachidonic acid, formed via the lipoxygenase, cyclooxygenase (COX) and epoxygenase pathways, play an important role in the regulation of various pathophysiological processes, including inflammation and cancer. COX-2, the inducible isoform of COX, has emerged as the key enzyme regulating inflammation, and promises to play a considerable role in cancer. Although NSAIDs have been in use for centuries, the COX-2 selective inhibitors - coxibs - have emerged as potent anti-inflammatory drugs with fewer gastric side effects. As COX-2 plays a major role in neoplastic transformation and cancer growth, by downregulating apoptosis and promoting angiogenesis, invasion and metastasis, coxibs have a potential role in the prevention and treatment of cancer. Recent studies indicate their possible application in overcoming drug resistance by downregulating the expression of MDR-1. However, the cardiac side effects of some of the coxibs have limited their application in treating various inflammatory disorders and warrant the development of COX-2 inhibitors without side effects. This review will focus on the role of COX-2 in inflammation and cancer, with an emphasis on novel approaches to the development of COX-2 inhibitors without side effects.

PKA and Epac cooperate to augment bradykinin-induced interleukin-8 release from human airway smooth muscle cells

BACKGROUND

Airway smooth muscle contributes to the pathogenesis of pulmonary diseases by secreting inflammatory mediators such as interleukin-8 (IL-8). IL-8 production is in part regulated via activation of Gq-and Gs-coupled receptors. Here we study the role of the cyclic AMP (cAMP) effectors protein kinase A (PKA) and exchange proteins directly activated by cAMP (Epac1 and Epac2) in the bradykinin-induced IL-8 release from a human airway smooth muscle cell line and the underlying molecular mechanisms of this response.

METHODS

IL-8 release was assessed via ELISA under basal condition and after stimulation with bradykinin alone or in combination with fenoterol, the Epac activators 8-pCPT-2'-O-Me-cAMP and Sp-8-pCPT-2'-O-Me-cAMPS, the PKA activator 6-Bnz-cAMP and the cGMP analog 8-pCPT-2'-O-Me-cGMP. Where indicated, cells were pre-incubated with the pharmacological inhibitors Clostridium difficile toxin B-1470 (GTPases), U0126 (extracellular signal-regulated kinases ERK1/2) and Rp-8-CPT-cAMPS (PKA). The specificity of the cyclic nucleotide analogs was confirmed by measuring phosphorylation of the PKA substrate vasodilator-stimulated phosphoprotein. GTP-loading of Rap1 and Rap2 was evaluated via pull-down technique. Expression of Rap1, Rap2, Epac1 and Epac2 was assessed via western blot. Downregulation of Epac protein expression was achieved by siRNA. Unpaired or paired two-tailed Student's t test was used.

RESULTS

The beta2-agonist fenoterol augmented release of IL-8 by bradykinin. The PKA activator 6-Bnz-cAMP and the Epac activator 8-pCPT-2'-O-Me-cAMP significantly increased bradykinin-induced IL-8 release. The hydrolysis-resistant Epac activator Sp-8-pCPT-2'-O-Me-cAMPS mimicked the effects of 8-pCPT-2'-O-Me-cAMP, whereas the negative control 8-pCPT-2'-O-Me-cGMP did not. Fenoterol, forskolin and 6-Bnz-cAMP induced VASP phosphorylation, which was diminished by the PKA inhibitor Rp-8-CPT-cAMPS. 6-Bnz-cAMP and 8-pCPT-2'-O-Me-cAMP induced GTP-loading of Rap1, but not of Rap2. Treatment of the cells with toxin B-1470 and U0126 significantly reduced bradykinin-induced IL-8 release alone or in combination with the activators of PKA and Epac. Interestingly, inhibition of PKA by Rp-8-CPT-cAMPS and silencing of Epac1 and Epac2 expression by specific siRNAs largely decreased activation of Rap1 and the augmentation of bradykinin-induced IL-8 release by both PKA and Epac.

CONCLUSION

Collectively, our data suggest that PKA, Epac1 and Epac2 act in concert to modulate inflammatory properties of airway smooth muscle via signaling to the Ras-like GTPase Rap1 and to ERK1/2.

Human airway smooth muscle cells from asthmatic individuals have CXCL8 hypersecretion due to increased NF-kappa B p65, C/EBP beta, and RNA polymerase II binding to the CXCL8 promoter

CXCL8 is a neutrophil and mast cell chemoattractant that is involved in regulating inflammatory cell influx in asthma. Here, we investigated the transcriptional mechanism involved in CXCL8 induction by TNF-alpha in cultured human airway smooth muscle (HASM) cells and compared these in cells from nonasthmatic and asthmatic individuals. Transfection studies with mutated CXCL8 promoter constructs identified NF-kappaB, activating protein-1, and CAAT/enhancer binding protein (C/EBP)beta as key transcription factors, and binding of these three transcription factors to the CXCL8 promoter after TNF-alpha stimulation was confirmed by chromatin immunoprecipitation analysis. Cells derived from asthmatic individuals produced significantly higher levels of CXCL8 than nonasthmatic cells both basally and following 24 h of stimulation with TNF-alpha (p < 0.001). Furthermore, chromatin immunoprecipitation studies detected increased binding of NF-kappaB p65 and RNA polymerase II to the CXCL8 promoter of asthmatic HASM cells both in the presence and absence of TNF-alpha stimulation. This was not due to either an increased activation or phosphorylation of NF-kappaB per se or to an increase in its translocation to the nucleus. Increased binding of C/EBPbeta to the CXCL8 promoter of unstimulated cells was also detected in the asthmatic HASM cells. Collectively these studies show that HASM cells from asthmatic individuals have increased CXCL8 production due to the presence of a transcription complex on the CXCL8 promoter, which contains NF-kappaB, C/EBPbeta, and RNA polymerase II. This is the first description of an abnormality in transcription factor binding altering chemokine expression in airway structural cells in asthma.

Mechanistic systems biology of inflammatory gene expression in airway smooth muscle as tool for asthma drug development

There is compelling evidence that airway smooth muscle cells may function as inflammatory cells in the airway system by producing multiple inflammatory cytokines in response to a large array of external stimuli such as acetylcholine, bradykinin, inflammatory cytokines, and toll-like receptor activators. However, how multiple extracellular stimuli interact in the regulation of inflammatory gene expression in an airway smooth muscle cell remains poorly understood. This review addresses the mechanistic systems biology of inflammatory gene expression in airway smooth muscle by discussing: a) redundancy underlying multiple stimulus-product relations in receptor-mediated inflammatory gene expression, and their regulation by convergent activation of Erk1/2 mitogen-activated protein kinase (MAPK), b) Erk1/2 MAPK-dependent induction of phosphatase expression as a negative feedback mechanism in the robust maintenance of inflammatory gene expression, and c) cyclooxygenase 2-dependent regulation of the differential temporal dynamics of early and late inflammatory gene expression. It is becoming recognized that a single-target approach is unlikely to be effective for the treatment of inflammatory airway diseases because airway inflammation is a result of complex interactions among multiple inflammatory mediators and cells types in the airway system. Understanding the mechanistic systems biology of inflammatory gene expression in airway smooth muscle and other cell types in the airway system may lead to the development of multi-target drug regimens for the treatment of inflammatory airway diseases such as asthma.

Hyperinduction of cyclooxygenase-2-mediated proinflammatory cascade: a mechanism for the pathogenesis of avian influenza H5N1 infection

The mechanism for the pathogenesis of H5N1 infection in humans remains unclear. This study reveals that cyclooxygenase-2 (COX-2) was strongly induced in H5N1-infected macrophages in vitro and in epithelial cells of lung tissue samples obtained during autopsy of patients who died of H5N1 disease. Novel findings demonstrated that COX-2, along with tumor necrosis factor alpha and other proinflammatory cytokines were hyperinduced in epithelial cells by secretory factors from H5N1-infected macrophages in vitro. This amplification of the proinflammatory response is rapid, and the effects elicited by the H5N1-triggered proinflammatory cascade are broader than those arising from direct viral infection. Furthermore, selective COX-2 inhibitors suppress the hyperinduction of cytokines in the proinflammatory cascade, indicating a regulatory role for COX-2 in the H5N1-hyperinduced host proinflammatory cascade. These data provide a basis for the possible development of novel therapeutic interventions for the treatment of H5N1 disease, as adjuncts to antiviral drugs.

Differential regulation of CCL-11/eotaxin-1 and CXCL-8/IL-8 by gram-positive and gram-negative bacteria in human airway smooth muscle cells

BACKGROUND

Bacterial infections are a cause of exacerbation of airway disease. Airway smooth muscle cells (ASMC) are a source of inflammatory cytokines/chemokines that may propagate local airway inflammatory responses. We hypothesize that bacteria and bacterial products could induce cytokine/chemokine release from ASMC.

METHODS

Human ASMC were grown in culture and treated with whole bacteria or pathogen associated molecular patterns (PAMPs) for 24 or 48 h. The release of eotaxin-1, CXCL-8 or GMCSF was measured by ELISA.

RESULTS

Gram-negative E. coli or gram-positive S. aureus increased the release of CXCL-8, as did IL-1beta, LPS, FSL-1 and Pam3CSK4, whereas FK565, MODLys18 or Poly I:C did not. E. coli inhibited eotaxin-1 release under control conditions and after stimulation with IL-1beta. S. aureus tended to inhibit eotaxin-1 release stimulated with IL-1beta. E. coli or LPS, but not S. aureus, induced the release of GMCSF.

CONCLUSION

Gram-positive or gram-negative bacteria activate human ASMC to release CXCL-8. By contrast gram-negative bacteria inhibited the release of eotaxin-1 from human ASMCs. E. coli, but not S. aureus induced GMCSF release from cells. Our findings that ASMC can respond directly to gram-negative and gram-positive bacteria by releasing the neutrophil selective chemokine, CXCL-8, is consistent with what we know about the role of neutrophil recruitment in bacterial infections in the lung. Our findings that bacteria inhibit the release of the eosinophil selective chemokine, eotaxin-1 may help to explain the mechanisms by which bacterial immunotherapy reduces allergic inflammation in the lung.

Transforming growth factor beta 1 increases fibronectin deposition through integrin receptor alpha 5 beta 1 on human airway smooth muscle

BACKGROUND

Integrin receptors signal to and from the extracellular matrix. Altered expression of the integrin receptors, such as the fibronectin receptor alpha(5)beta(1), might be implicated in extracellular matrix accumulation in airway remodeling in asthma.

OBJECTIVE

We examined the effect of TGF-beta stimulation on integrin alpha(5)beta(1) expression and the role of alpha(5)beta(1) in fibronectin deposition and proliferation.

METHODS

Integrin subunit alpha(5) and beta(1) expression in airway smooth muscle (ASM) from subjects with and without asthma was examined by means of PCR and flow cytometry. The effect of blocking alpha(5)beta(1) receptor on ASM proliferation to FBS was assessed by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium assay. Cells were stimulated with TGF-beta in the presence or absence of extracellular signal-regulated kinase, phosphoinositide-3 kinase, or p38 inhibitors and antibodies to the alpha(5) and beta(1) subunits. The effect of blocking alpha(5)beta(1) receptor on fibronectin deposition was assessed by means of immunocytochemistry.

RESULTS

Proliferation of ASM cells from asthmatic and nonasthmatic subjects was inhibited by blocking the fibronectin receptor subunit alpha(5)beta(1). TGF-beta-induced alpha(5)beta(1) was extracellular signal-regulated kinase dependent but not phosphoinositide-3 kinase or p38 dependent. Blockade of the alpha(5)beta(1) receptor inhibited TGF-beta-induced fibronectin matrix deposition.

CONCLUSION

Through its increased expression by the profibrotic stimulus TGF-beta, integrin alpha(5)beta(1) might be important in regulating fibronectin deposition.

Transforming growth factor- 1 C-509T polymorphism, oxidant stress, and early-onset childhood asthma

RATIONALE

Transforming growth factor (TGF)-beta1 is involved in airway inflammation and remodeling, two key processes in asthma pathogenesis. Tobacco smoke and traffic emissions induce airway inflammation and modulate TGF-beta1 gene expression. We hypothesized that the effects of functional TGF-beta1 variants on asthma occurrence vary by these exposures.

OBJECTIVES

We tested these hypotheses among 3,023 children who participated in the Children's Health Study.

METHODS

Tagging single-nucleotide polymorphisms rs4803457 C>T and C-509T (a functional promoter polymorphism) accounted for 94% of the haplotype diversity of the upstream region. Exposure to maternal smoking in utero was based on smoking by biological mother during pregnancy. Residential distance from nearest freeway was calculated based on residential address at study entry.

MEASUREMENTS AND MAIN RESULTS

Children with the -509TT genotype had a 1.8-fold increased risk of early persistent asthma (95% confidence interval [CI], 1.11-2.95). This association varied marginally significantly by in utero exposure to maternal smoking. Compared with children with the -509CC/CT genotype with no in utero exposure to maternal smoking, those with the -509TT genotype with such exposure had a 3.4-fold increased risk of early persistent asthma (95% CI, 1.46-7.80; interaction, P = 0.11). The association between TGF-beta1 C-509T and lifetime asthma varied by residential proximity to freeways (interaction P = 0.02). Children with the -509TT genotype living within 500 m of a freeway had over three-fold increased lifetime asthma risk (95% CI, 1.29-7.44) compared with children with CC/CT genotype living > 1500 m from a freeway.

CONCLUSIONS

Children with the TGF-beta1 -509TT genotype are at increased risk of asthma when they are exposed to maternal smoking in utero or to traffic-related emissions.

Fluticasone, but not salmeterol, reduces cigarette smoke-induced production of interleukin-8 in human airway smooth muscle

Cigarette smoke is the leading risk factor for the development of chronic obstructive pulmonary disease. We have recently shown that cigarette smoke extract synergises with tumour necrosis factor alpha (TNFalpha) in the induction of interleukin-8 (IL-8) from human airway smooth muscle cells. We have investigated the effect of fluticasone propionate, a corticosteroid, and salmeterol, a beta 2-adrenergic receptor agonist, on cigarette smoke extract-induced IL-8 production by human airway smooth muscle cells. Human airway smooth muscle cells in primary culture were exposed to cigarette smoke extract and/or TNFalpha (1 ng ml(-1)) with and without pretreatment with fluticasone (10(-13)-10(-8)M) and/or salmeterol (10(-11)-10(-6)M). IL-8 was analysed by ELISA. Fluticasone dose-dependently inhibited IL-8 release induced by cigarette smoke extract, TNFalpha or combined cigarette smoke extract and TNFalpha. However, while IL-8 release in the presence of cigarette smoke extract alone was completely inhibited by fluticasone, IL-8 production induced by cigarette smoke extract and TNFalpha was only partially reduced. Salmeterol alone had no effect on cigarette smoke extract and/or TNFalpha-induced IL-8 production from human airway smooth muscle cells. Combined fluticasone and salmeterol did not cause further inhibitory effects compared to fluticasone alone. Fluticasone but not salmeterol is effective in reducing cigarette smoke extract-induced IL-8 production in human airway smooth muscle cells. The reduced inhibition of cigarette smoke extract- and TNFalpha-induced IL-8 release by fluticasone may explain why corticosteroids are less effective in chronic obstructive pulmonary disease where increased amounts of TNFalpha are present.

Effect of interleukin-4 on vascular endothelial growth factor production in rheumatoid synovial fibroblasts

Interleukin (IL)-4 has been demonstrated to have anti-inflammatory and anti-tumour activity. Because aberrant angiogenesis is a significant pathogenic component of tumour growth and chronic inflammation, we investigated the effect of IL-4 on the production of vascular endothelial growth factor (VEGF) by synovial fibroblasts derived from patients with rheumatoid arthritis (RA). Fibroblast-like synoviocytes (FLS) were prepared from synovial tissues of RA and incubated with different concentrations of IL-4 in the presence or absence of transforming growth factor (TGF)-beta. VEGF level was measured by enzyme-linked immunosorbent assay and semiquantitative reverse transcription--polymerase chain reaction. Treatment of FLS with IL-4 alone caused a dose-dependent increase in VEGF levels. In contrast, IL-4 exhibited the inhibitory effect on VEGF production when FLS were stimulated with TGF-beta. Combined treatment of IL-4 and IL-10 inhibited TGF-beta-induced VEGF production in an additive fashion. TGF-beta increased the induction of cyclooxygenase-2 mRNA, which was inhibited significantly by the treatment of IL-4. NS-398, a COX-2 inhibitor, inhibited TGF-beta-induced VEGF production in a dose-dependent manner. Furthermore, exogenous addition of prostaglandin E2 (PGE2) restored IL-4 inhibition on TGF-beta induced VEGF production. Collectively, our results suggest that IL-4 have an anti-angiogenic effect, especially in the inflammatory milieu of RA by inhibiting the VEGF production in synovial fibroblasts.

Mode of action of natural and synthetic drugs against Trypanosoma cruzi and their interaction with the mammalian host

Current knowledge of the biochemistry of Trypanosoma cruzi has led to the development of new drugs and the understanding of their mode of action. Some trypanocidal drugs such as nifurtimox and benznidazole act through free radical generation during their metabolism. T. cruzi is very susceptible to the cell damage induced by these metabolites because enzymes scavenging free radicals are absent or have very low activities in the parasite. Another potential target is the biosynthetic pathway of glutathione and trypanothione, the low molecular weight thiol found exclusively in trypanosomatids. These thiols scavenge free radicals and participate in the conjugation and detoxication of numerous drugs. Inhibition of this key pathway could render the parasite much more susceptible to the toxic action of drugs such as nifurtimox and benznidazole without affecting the host significantly. Other drugs such as allopurinol and purine analogs inhibit purine transport in T. cruzi, which cannot synthesize purines de novo. Nitroimidazole derivatives such as itraconazole inhibit sterol metabolism. The parasite's respiratory chain is another potential therapeutic target because of its many differences with the host enzyme complexes. The pharmacological modulation of the host's immune response against T. cruzi infection as a possible chemotherapeutic target is discussed. A large set of chemicals of plant origin and a few animal metabolites active against T. cruzi are enumerated and their likely modes of action are briefly discussed.

The regulatory role of TGF-beta in airway remodeling in asthma

Both structural and inflammatory cells are capable of secreting transforming growth factor (TGF)-beta and expressing TGF-beta receptors. TGF-beta can induce multiple cellular responses including differentiation, apoptosis, survival and proliferation, and has been implicated in the development of several pathogenic conditions including cancer and asthma. Elevated levels of TGF-beta have been reported in the asthmatic airway. TGF-beta binds to its receptor complex and activates multiple pathways involving proteins such as Sma and Mad homologues, phosphatidylinositol-3 kinase and the mitogen-activated protein kinases, leading to the transcription of several genes. Cell type, cellular condition, and microenvironment, all play a role in determining which pathway is activated, which, in turn, is an indication of which gene is to be transcribed. TGF-beta has been shown to induce apoptosis in airway epithelial cells. A possible role for TGF-beta in the regulation of epithelial cell adhesion properties has also been reported. Enhancement of goblet cell proliferation by TGF-beta suggests a role in mucus hyper-secretion. Elevated levels of TGF-beta correlate with subepithelial fibrosis. TGF-beta induces proliferation of fibroblast cells and their differentiation into myofibroblasts and extracellular matrix (ECM) protein synthesis during the development of subepithelial fibrosis. TGF-beta also induces proliferation and survival of and ECM secretion in airway smooth muscle cells (ASMCs), suggesting a possible cause of increased thickness of airway tissues. TGF-beta also induces the production and release of vascular endothelial cell growth factor and plasminogen activator inhibitor, contributing to the vascular remodeling in the asthmatic airway. Blocking TGF-beta activity inhibits epithelial shedding, mucus hyper-secretion, angiogenesis, ASMC hypertrophy and hyperplasia in an asthmatic mouse model. Reduction of TGF-beta production and control of TGF-beta effects would be beneficial in the development of therapeutic intervention for airway remodeling in chronic asthma.

Non-steroidal anti-inflammatory drugs to potentiate chemotherapy effects: from lab to clinic

Most solid tumors express the cyclooxygenase-2 (COX-2) protein, a target of NSAIDs. COX-2 overexpression in tumorsis considered a predictor of more advanced stage disease and of worse prognosis in a number of studies investigating solid malignancies. Therefore, NSAIDs are evaluated as anti-cancer drugs. NSAIDs inhibit proliferation, invasiveness of tumors, and angiogenesis and overcome apoptosis resistance in a COX-2 dependent and independent manner. This review will focus on the rationale behind NSAIDs, including selective COX-2 inhibitors, in combination with conventional chemotherapeutic drugs or novel molecular targeted drugs. Studies investigating anti-cancer effects of NSAIDs on cell lines and xenograft models have shown modulation of the Akt, NF-kappaB, tyrosine kinase and the death receptor-mediated apoptosis pathways. COX-2 expression in tumors is not yet used as biomarker in the clinic. Despite the increased risk on cardiovascular toxicity induced by selective COX-2 inhibitors, several ongoing clinical trials are still investigating the therapeutic benefits of NSAIDs in oncology. The anti-tumor effects in these trials balanced with the side effects data will define the precise role of selective COX-2 inhibitors in the treatment of cancer patients.

Nerve fibres in peritoneal endometriosis

BACKGROUND

Endometriosis is a gynaecological disease that can be associated with severe pelvic pain; however, the mechanisms by which pain is generated remain unknown.

METHODS

Peritoneal endometriotic lesions and normal peritoneum were prepared from women with and without endometriosis (n = 40 and 36, respectively). Specimens were also prepared from endosalpingiosis lesions (n = 9). These sections were stained immunohistochemically with antibodies against protein gene product 9.5, neurofilament (NF), nerve growth factor (NGF), NGF receptor p75 (NGFRp75), substance P (SP), calcitonin gene-related peptide (CGRP), acetylcholine (ACh) and tyrosine hydroxylase (TH) to demonstrate myelinated, unmyelinated, sensory, cholinergic and adrenergic nerve fibres.

RESULTS

There were significantly more nerve fibres identified in peritoneal endometriotic lesions than in normal peritoneum (P < 0.001) or endosalpingiosis lesions (P < 0.001). These nerve fibres were SP, CGRP, ACh or TH immunoreactive. Many of these markers were co-localized. There was an intense NGF immunoreactivity near endometriotic glands, and NGFRp75 immunoreactive nerve fibres were present near endometriotic glands and blood vessels in the peritoneal endometriotic lesions.

CONCLUSIONS

Peritoneal endometriotic lesions were innervated by sensory Adelta, sensory C, cholinergic and adrenergic nerve fibres. These nerve fibres may play an important role in the mechanisms of pain generation in this condition.

Increased Expression of Cyclooxygenase-2 (COX-2) in Radiation-Induced Small Bowel Injury in Rats

BACKGROUND

Radiation therapy is a widely used adjuvant therapy for various abdominal and pelvic cancers. On the other hand, it is not a benign treatment modality, as most radiation patients suffer from some kind of radiation enteritis. Currently available treatments are only palliative and no ideal compound has as yet been discovered. The aim of this study was to evaluate cyclooxygenase-2 (COX-2) expression, and to investigate the possible protective effect of the selective COX-2 inhibitor, Rofecoxib, in acute and late stages of radiation-induced intestinal injury in rats.

MATERIALS AND METHODS

Forty-eight male Sprague-Dawley rats were randomly divided into eight groups. After abdominal irradiation of all of the animals except the six in the control group, the expression of the enzyme cyclooxygenase-2 (COX-2) was evaluated in different cell types present in the intestinal wall 2 h post exposure (study day 0) and again on study days 4, 14, and 60. The effects of Rofecoxib on histological damage, intestinal myeloperoxidase (MPO) activity, and malondialdehyde (MDA) levels were also measured.

RESULTS

Expression of COX-2 in vascular endothelial cells was found to be significantly increased on post exposure days 4 and 14 (2.4 and 2.9 stained vessels/high power field [hpf] respectively compared to 1.3 vessels/hpf for controls) (P = 0.002). Expression of COX-2 in fibroblasts increased immediately after irradiation (29 cells/hpf 2 h after irradiation compared to 12 cells/hpf for non-irradiated control animals) and remained high during the entire study period (P < 0.001), whereas there was a peak COX-2 expression (54.9 cells/hpf) on day 14 that was similar to what was observed in endothelial cells. Irradiation of rats significantly increased intestinal epithelial damage, MPO activity, and MDA levels in comparison to the control group in a time-dependent fashion. Treatment with rofecoxib significantly decreased these elevations except on day 4 of the study.

CONCLUSION

The current study suggests that the COX-2 pathway is involved in radiation induced intestinal injury and that targeting COX-2 may be useful in limiting radiation enteritis.

Cyclooxygenases in hepatocellular carcinoma

Many epidemiological studies demonstrate that treatment with non-steroidal anti-inflammatory drugs (NSAIDs) reduce the incidence and mortality of certain malignancies, especially gastrointestinal cancer. The cyclooxygenase (COX) enzymes are well-known targets of NSAIDs. However, conventional NSAIDs non-selectively inhibit both the constitutive form COX-1, and the inducible form COX-2. Recent evidence indicates that COX-2 is an important molecular target for anticancer therapies. Its expression is undetectable in most normal tissues, and is highly induced by pro-inflammatory cytokines, mitogens, tumor promoters and growth factors. It is now well-established that COX-2 is chronically overexpressed in many premalignant, malignant, and metastastic cancers, including hepatocellular carcinoma (HCC). Overexpression of COX-2 in patients with HCC is generally higher in well-differentiated HCCs compared with less-differentiated HCCs or histologically normal liver, suggesting that COX-2 may be involved in the early stages of hepatocarcinogenesis, and increased expression of COX-2 in noncancerous liver tissue has been significantly associated with shorter disease-free survival in patients with HCC.

In tumors, overexpression of COX-2 leads to an increase in prostaglandin (PG) levels, which affect many mechanisms involved in carcinogenesis, such as angiogenesis, inhibition of apoptosis, stimulation of cell growth as well as the invasiveness and metastatic potential of tumor cells.

The availability of novel agents that selectively inhibit COX-2 (COXIB), has contributed to shedding light on the role of this molecule. Experimental studies on animal models of liver cancer have shown that NSAIDs, including both selective and non-selective COX-2 inhibitors, exert chemopreventive as well as therapeutic effects. However, the key mechanism by which COX-2 inhibitors affect HCC cell growth is as yet not fully understood.

Increasing evidence suggests the involvement of molecular targets other than COX-2 in the anti-proliferative effects of COX-2 selective inhibitors. Therefore, COX-inhibitors may use both COX-2-dependent and COX-2-independent mechanisms to mediate their antitumor properties, although their relative contributions toward the in vivo effects remain less clear.

Here we review the features of COX enzymes, the role of the expression of COX isoforms in hepatocarcinogenesis and the mechanisms by which they may contribute to HCC growth, the pharmacological properties of COX-2 selective inhibitors, the antitumor effects of COX inhibitors, and the rationale and feasibility of COX-2 inhibitors for the treatment of HCC.

Beneficial Effect of TGFβ Antagonism in Treating Diabetic Nephropathy Depends on When Treatment Is Started

BACKGROUND

In diabetic rats with maximal activation of RAS induced by uninephrectomy, late treatment with anti-TGFbeta antibody limited renal injury only when combined with ACE inhibitor. We investigated whether in a two-kidney diabetic model the time at which treatment started predicted the response to TGFbeta antagonist.

METHODS

27 weeks after streptozotocin injection, animals had mild proteinuria and were randomized to receive irrelevant antibody, anti-TGFbeta antibody (1D11) or enalapril till 52 weeks (early treatment). The effect of agents alone or combined was also evaluated at the time of overt proteinuria (late treatment, 52-61 weeks).

RESULTS

When given early, 1D11 displayed marked antihypertensive and antiproteinuric effects. Glomerulosclerosis was reduced to the extent that a remarkable percentage of glomeruli without sclerosis appeared after treatment. Podocyte number was normalized. Renoprotection of 1D11 was comparable to enalapril. Despite control of blood pressure, in late treatment single agents did not reduce proteinuria significantly. Glomerulosclerosis and podocyte loss were partially limited by 1D11 or enalapril, but full protection was achieved by combination.

CONCLUSIONS

Renoprotective effect of TGFbeta antagonism crucially depends on the time at which treatment started. Effectiveness of early treatment with 1D11 would indicate that TGFbeta is a major mediator of damage in early diabetes. To tackle the renal damage in the phase of advanced disease, a combined treatment with ACE inhibitor is needed.

Effects of transforming growth factor-beta in the development of inflammatory pseudotumour-like lesions in a murine model

Alterations in transforming growth factor (TGF)-beta signalling have been frequently implicated in human cancer, and an important mechanism underlying its pro-oncogenic nature is suppression of the host antitumour immune response. Considering the immunosuppressive effect of TGF-beta, we asked whether human tumour cells, known to secrete TGF-beta in culture, would survive and grow when implanted into the peritoneal cavity of immunocompetent mice. Therefore, we developed a xenogeneic model where mice were intraperitoneally (i.p.) injected with a TGF-beta-secreting human colorectal adenocarcinoma cell line, LISP-A10. Although animals did not develop macroscopic tumours, the recovery and isolation of human tumour cells was achieved when an inflammatory environment was locally induced by the administration of complete Freund's adjuvant (CFA). This procedure significantly increased TGF-beta concentrations in the peritoneal fluid and was accompanied by impaired activation of the host-specific immune response against LISP-A10 cells. Furthermore, inflammatory lesions resembling human inflammatory pseudotumours (IPTs) were observed on the surface of i.p. organs. These lesions could be induced by either injection of LISP-A10 cells, cells-conditioned medium or recombinant TGF-beta but only after administration of CFA. In addition, host cyclooxygenase-2 and kinin receptors played an important role in the induction of TGF-beta-mediated IPT-like lesions in our experimental model.

Prospects of antiviral and anti-inflammatory therapy for respiratory syncytial virus infection

Respiratory syncytial virus is the leading viral cause of death in children less than 2 years of age, and is an increasing cause of morbidity and mortality in transplant patients and the elderly. Respiratory syncytial virus causes upper and lower respiratory tract infections, which can lead to severe bronchiolitis and pneumonia. High-risk groups for severe respiratory syncytial virus infection include infants with a history of premature birth with or without chronic lung disease, children with congenital heart disease, children with cystic fibrosis or chronic lung diseases, and immunosuppressed patients or patients with immunodeficiency. However, the majority of infants who have severe respiratory syncytial virus disease are born at full term and are otherwise healthy. It is unclear why children, the elderly and the immunosuppressed are at much higher risk for severe disease; however, a respiratory syncytial virus-induced immune pathologic mechanism has long been suspected. Attempts to develop a safe and effective vaccine against respiratory syncytial virus have failed. Antirespiratory syncytial virus immunotherapy, although effective prophylactically, does not provide any beneficial clinical outcome when administered therapeutically, indicating that respiratory syncytial virus-induced pathology is most likely the result of the inflammatory response to infection, rather than a direct viral cytopathic effect. Thus, a combined antiviral and anti-inflammatory therapy may represent the safest and most efficient treatment for acute respiratory syncytial virus infection. In this review, the current knowledge that has set the rationale for the development of such therapy is summarized.