Pulmonary hypertension and vascular remodeling in mice exposed to crystalline silica

Impact of soluble epoxide hydrolase inhibition on silica-induced pulmonary fibrosis, ectopic lymphoid neogenesis, and autoantibody production in lupus-prone mice

OBJECTIVE

Acute intranasal (IN) instillation of lupus-prone NZBWF1 mice with crystalline silica (cSiO2) triggers robust lung inflammation that drives autoimmunity. Prior studies in other preclinical models show that soluble epoxide hydrolase (sEH) inhibition upregulates pro-resolving lipid metabolites that are protective against pulmonary inflammation. Herein, we assessed in NZBWF1 mice how acute IN cSiO2 exposure with or without the selective sEH inhibitor TPPU influences lipidomic, transcriptomic, proteomic, and histopathological biomarkers of inflammation, fibrosis, and autoimmunity.

METHODS

Female 6-week-old NZBWF1 mice were fed control or TPPU-supplemented diets for 2 weeks then IN instilled with 2.5 mg cSiO2 or saline vehicle. Cohorts were terminated at 7 or 28 days post-cSiO2 instillation (PI) and lungs analyzed for prostaglandins, cytokines/chemokines, gene expression, differential cell counts, histopathology, and autoantibodies.

RESULTS

cSiO2-treatment induced prostaglandins, cytokines/chemokine, proinflammatory gene expression, CD206+ monocytes, Ly6B.2+ neutrophils, CD3+ T cells, CD45R+ B cells, centriacinar inflammation, collagen deposition, ectopic lymphoid structure neogenesis, and autoantibodies. While TPPU effectively inhibited sEH as reflected by skewed lipidomic profile in lung and decreased cSiO2-induced monocytes, neutrophils, and lymphocytes in lung lavage fluid, it did not significantly impact other biomarkers.

DISCUSSION

cSiO2 evoked robust pulmonary inflammation and fibrosis in NZBWF1 mice that was evident at 7 days PI and progressed to ELS development and autoimmunity by 28 days PI. sEH inhibition by TPPU modestly suppressed cSiO2-induced cellularity changes and pulmonary fibrosis. However, TPPU did not affect ELS formation or autoantibody responses, suggesting sEH minimally impacts cSiO2-triggered lung inflammation, fibrosis, and early autoimmunity in our model.

Logistic regression model for predicting risk factors and contribution of cerebral microbleeds using renal function indicators

Background

The brain and kidneys share similar low-resistance microvascular structures, receiving blood at consistently high flow rates and thus, are vulnerable to blood pressure fluctuations. This study investigates the causative factors of cerebral microbleeds (CMBs), aiming to quantify the contribution of each risk factor by constructing a multivariate model via stepwise regression.

Methods

A total of 164 hospitalized patients were enrolled from January 2022 to March 2023 in this study, employing magnetic susceptibility-weighted imaging (SWI) to assess the presence of CMBs. The presence of CMBs in patients was determined by SWI, and history, renal function related to CMBs were analyzed.

Results

Out of 164 participants in the safety analysis, 36 (21.96%) exhibited CMBs and 128 (78.04%) did not exhibit CMBs, and the median age of the patients was 66 years (range: 49-86 years). Multivariate logistic regression identified hypertension (OR = 13.95%, 95% CI: 4.52, 50.07%), blood urea nitrogen (BUN) (OR = 1.57, 95% CI: 1.06-2.40), cystatin C (CyC) (OR = 4.90, 95% CI: 1.20-22.16), and urinary β-2 microglobulin, (OR = 2.11, 95% CI: 1.45-3.49) as significant risk factors for CMBs. The marginal R-square (R M 2 ) was 0.25. Among all determinants, hypertension (47.81%) had the highest weight, followed by UN (11.42%). Quasi-curves plotted using the bootstrap method (999 times) showed good agreement between the predictive model and actual observations.

Conclusion

Hypertension, BUN, urinary β-2 microglobulin, CyC were risk factors for CMBs morbidity, and controlling the above indicators within a reasonable range will help to reduce the incidence of CMBs.

Association of complete blood count parameters with the risk of incident pulmonary heart disease in pneumoconiosis: a retrospective cohort study

BACKGROUND

Pneumoconiosis mostly combines pulmonary and cardiovascular diseases, among which pulmonary heart disease (PHD) is of major concern due to its significant impact on the survival of pneumoconiosis patients. White cell count (WCC), red cell distribution width (RDW) and platelet parameters are thought to affect inflammatory responses and may be predictors of various cardiovascular diseases. However, very few studies have focused on PHD.

OBJECTIVES

To examine the relationship between baseline complete blood count parameters (WCC, RDW, platelet parameters) and the risk of incident PHD in pneumoconiosis patients.

DESIGN

A retrospective cohort study.

SETTING

This was a single-centre, retrospective cohort study that used data from an Occupational Disease Hospital, Chengdu, Sichuan.

PARTICIPANTS

A total of 946 pneumoconiosis patients from January 2012 to November 2021 were included in the study. Female patients and patients who had PHD, coronary heart disease, hypertensive heart disease, cardiomyopathy, heart failure, oncological disease, multiple organ dysfunction, AIDS at baseline and follow-up time of less than 6 months were also excluded.

OUTCOME MEASURES

We identified PHD according to the patient's discharge diagnosis. We constructed Cox proportional hazard regression models to assess the HR of incident PHD in pneumoconiosis, as well as 95% CIs.

RESULTS

In the multiple Cox proportional hazard regression analysis, platelet count (PLT) and plateletcrit (PCT) above the median at baseline were associated with an increased risk of PHD in pneumoconiosis with adjusted HR of 1.52 (95% CI 1.09 to 2.12) and 1.42 (95% CI 1.02 to 1.99), respectively.

CONCLUSION

Higher baseline PLT and PCT are associated with a higher risk of PHD in pneumoconiosis.

Pulmonary osteoclast-like cells in silica induced pulmonary fibrosis

The pathophysiology of silicosis is poorly understood, limiting development of therapies for those who have been exposed to the respirable particle. We explored mechanisms of silica-induced pulmonary fibrosis in human lung samples collected from patients with occupational exposure to silica and in a longitudinal mouse model of silicosis using multiple modalities including whole-lung single-cell RNA sequencing and histological, biochemical, and physiologic assessments. In addition to pulmonary inflammation and fibrosis, intratracheal silica challenge induced osteoclast-like differentiation of alveolar macrophages and recruited monocytes, driven by induction of the osteoclastogenic cytokine, receptor activator of nuclear factor κΒ ligand (RANKL) in pulmonary lymphocytes, and alveolar type II cells. Anti-RANKL monoclonal antibody treatment suppressed silica-induced osteoclast-like differentiation in the lung and attenuated pulmonary fibrosis. We conclude that silica induces differentiation of pulmonary osteoclast-like cells leading to progressive lung injury, likely due to sustained elaboration of bone-resorbing proteases and hydrochloric acid. Interrupting osteoclast-like differentiation may therefore constitute a promising avenue for moderating lung damage in silicosis.

Impact of Respiratory Dust on Health: A Comparison Based on the Toxicity of PM2.5, Silica, and Nanosilica

Respiratory dust of different particle sizes in the environment causes diverse health effects when entering the human body and makes acute or chronic damage through multiple systems and organs. However, the precise toxic effects and potential mechanisms induced by dust of different particle sizes have not been systematically summarized. In this study, we described the sources and characteristics of three different particle sizes of dust: PM2.5 (<2.5 μm), silica (<5 μm), and nanosilica (<100 nm). Based on their respective characteristics, we further explored the main toxicity induced by silica, PM2.5, and nanosilica in vivo and in vitro. Furthermore, we evaluated the health implications of respiratory dust on the human body, and especially proposed potential synergistic effects, considering current studies. In summary, this review summarized the health hazards and toxic mechanisms associated with respiratory dust of different particle sizes. It could provide new insights for investigating the synergistic effects of co-exposure to respiratory dust of different particle sizes in mixed environments.

Prevalence of pulmonary hypertension in chronic simple silicosis patients and its correlation with smoking history, occupation type, age and duration of silica exposure

Silicosis is a preventable occupational health hazard with potential for permanent physical disability and increased socio-economic burden. Pulmonary hypertension (PH) secondary to chronic respiratory diseases signifies poorer prognosis and transthoracic echocardiography (TTE) has proven its usefulness as a screening tool for PH diagnosis. The objectives were to determine PH prevalence in chronic simple silicosis patients through TTE screening and correlate PH prevalence with smoking status, occupation type, age and duration of silica exposure (DSE). We enrolled 104 patients in the study based on occupational exposure to silica dust and radiologic confirmation of chronic simple silicosis. The study sample was divided into significant smokers (SS group) and insignificant smokers (InS group) on the basis of ≥10 pack years smoking history, and into drillers and dressers based on occupation type. TTE examination was performed to measure resting mean pulmonary artery pressure (mPAP) and the patients were classified into: no PH (mPAP≤20 mm Hg), borderline PH (mPAP>20 and <25 mmHg), and PH (mPAP≥25). PH prevalence was 25% in study subjects (26/104); 29.6% (16/54) among SS group versus 20% (10/50) among InS group (.52) ; and 34.2% (14/41) among drillers versus 19.1% (12/63) among dressers (p=.024). Mean age and mean duration of silica exposure among SS and InS groups were comparatively similar, while they had lower values among dressers against dressers with no statistical significance. Logistic regression analysis established a significant association of PH prevalence with higher age in the study sample, SS group and drillers group, while a significant association of PH prevalence with longer DSE was only seen in the study sample. PH prevalence was significantly associated (p=.007) with SS-driller group on comparing TTE findings with combined smoking and occupation type based groups. This study has shown PH prevalence in chronic simple silicosis patients at alarming levels, having associations with driller occupation, older age and longer DSE with varying results among groups and complex interplay with smoking exposure, suggesting the need for large sample-based molecular and genetic studies. Including TTE in the initial work-up of silicosis patients will promote timely intervention and reduce morbidity and mortality with a high benefit-cost ratio.

Potential Roles of Metals in the Pathogenesis of Pulmonary and Systemic Hypertension

Pulmonary and systemic hypertension (PH, SH) are characterized by vasoconstriction and vascular remodeling resulting in increased vascular resistance and pulmonary/aortic artery pressures. The chronic stress leads to inflammation, oxidative stress, and infiltration by immune cells. Roles of metals in these diseases, particularly PH are largely unknown. This review first discusses the pathophysiology of PH including vascular oxidative stress, inflammation, and remodeling in PH; mitochondrial dysfunction and metabolic changes in PH; ion channel and its alterations in the pathogenesis of PH as well as PH-associated right ventricular (RV) remodeling and dysfunctions. This review then summarizes metal general features and essentiality for the cardiovascular system and effects of metals on systemic blood pressure. Lastly, this review explores non-essential and essential metals and potential roles of their dyshomeostasis in PH and RV dysfunction. Although it remains early to conclude the role of metals in the pathogenesis of PH, emerging direct and indirect evidence implicates the possible contributions of metal-mediated toxicities in the development of PH. Future research should focus on comprehensive clinical metallomics study in PH patients; mechanistic evaluations to elucidate roles of various metals in PH animal models; and novel therapy clinical trials targeting metals. These important discoveries will significantly advance our understandings of this rare yet fatal disease, PH.

Perivascular inflammatory cells and their association with pulmonary arterial remodelling in dogs with pulmonary hypertension due to myxomatous mitral valve disease

Pulmonary hypertension (PH), an increase in pulmonary arterial pressure (PAP), may occur in dogs affected with myxomatous mitral valve disease (MMVD). Recent studies suggest that an accumulation of perivascular inflammatory cells may be involved with medial thickening which is a sign of the pulmonary artery remodelling in PH. The aim of this study was to characterise perivascular inflammatory cells in the surrounding pulmonary arteries of dogs with PH due to MMVD compared to MMVD dogs and healthy control dogs. Nineteen lung samples were collected from cadavers of small-breed dogs (control n = 5; MMVD n = 7; MMVD + PH n = 7). Toluidine blue stain and multiple IHC targeting α-SMA, vWF, CD20, CD68 and CD3 was performed to examine intimal and medial thickening, assess muscularisation of the small pulmonary arteries and characterise perivascular leucocytes. Medial thickening without intimal thickening of pulmonary arteries and muscularisation of normally non-muscularised small pulmonary arteries was observed in the MMVD and MMVD + PH groups compared with the control group. The perivascular numbers of B lymphocytes, T lymphocytes and macrophages was significantly increased in the MMVD + PH group compared with the MMVD and control groups. In contrast, the perivascular number of mast cells was significantly higher in the MMVD group compared with the MMVD + PH and control groups. This study suggested that pulmonary artery remodelling as medial thickening and muscularisation of the normally non-muscular small pulmonary arteries is accompanied by the accumulation of perivascular inflammatory cells.

Histopathological, biochemical and molecular studies on a model of systemic autoimmune disease induced by sodium silicate in non-genetically prone rats

Sodium silicate (Na2SiO₃) is an inorganic silica salt used in many products. Few studies reported autoimmune diseases (AIDs) due to Na2SiO₃ exposure. This study investigates the role of Na2SiO₃ exposure by different routes and doses in AID development in rats. We assigned 40 female rats to four groups: G1 control group, G2 rats were subcutaneously injected with 5 mg Na2SiO₃ suspension, and G3 and G4 rats were orally administered 5 mg and 7 mg Na2SiO₃ suspension, respectively. Na2SiO₃ was administered weekly for 20 weeks. Serum anti-nuclear antibodies (ANA) detection, histopathology of kidney, brain, lung, liver, and heart, oxidative stress biomarkers (MDA and GSH) in tissues, Matrix metalloproteinase activity in serum, TNF-α, and Bcl-2 expression in tissues were performed. ANA was significantly increased in silicate groups, especially G2. Creatinine was significantly increased in silicate groups. Histopathology revealed vasculitis and fibrinoid degeneration of blood vessels, a picture of immune-mediated glomerulonephritis in the kidneys, and chronic interstitial pneumonia with medial hypertrophy of pulmonary blood vessels. The activity of gelatinases (MMP-2 and MMP-9) and collagenase (MMP-13), which play role in inflammation, remodeling, and immune complex degradation, were significantly increased in the silicate-exposed groups. Bcl-2 was significantly decreased, indicating apoptosis. Therefore, oral administration and subcutaneous injection of Na2SiO₃ induced immune-mediated glomerulonephritis with elevated ANA levels and overexpression of TNF-α in rats.

Type 1 Pulmonary Hypertension and Silicosis in a Bluestone Cutter: A Case Report on Raising Awareness

This case report describes a patient who developed pneumoconiosis in the form of silicosis and group 1 pulmonary hypertension (PH) due to his unprotected work as a bluestone cutter. Bluestone is a type of sandstone used in outdoor construction commonly in the North-east region of the US. In the literature and to our knowledge, blue stone mining has not been viewed as a risk factor for pneumoconiosis. This case report aims to increase awareness about this occupational hazard. Additionally, it is known that chronic silicosis with massive pulmonary fibrosis can lead to hypoxemia and group 3 pulmonary hypertension. This case, however, demonstrates a possibility of silica dust exposure leading to group 1 pulmonary arterial hypertension.

Pulmonary osteoclast-like cells in silica induced pulmonary fibrosis

The pathophysiology of silicosis is poorly understood, limiting development of therapies for those who have been exposed to the respirable particle. We explored the mechanisms of silica-induced pulmonary fibrosis in a mouse model using multiple modalities including whole-lung single-nucleus RNA sequencing. These analyses revealed that in addition to pulmonary inflammation and fibrosis, intratracheal silica challenge induced osteoclast-like differentiation of alveolar macrophages and recruited monocytes, driven by induction of the osteoclastogenic cytokine, receptor activator of nuclear factor-κB ligand (RANKL) in pulmonary lymphocytes and alveolar type II cells. Furthermore, anti-RANKL monoclonal antibody treatment suppressed silica-induced osteoclast-like differentiation in the lung and attenuated silica-induced pulmonary fibrosis. We conclude that silica induces osteoclast-like differentiation of distinct recruited and tissue resident monocyte populations, leading to progressive lung injury, likely due to sustained elaboration of bone resorbing proteases and hydrochloric acid. Interrupting osteoclast-like differentiation may therefore constitute a promising avenue for moderating lung damage in silicosis.

Adenovirus-mediated Overexpression of FcγRIIB Attenuates Pulmonary Inflammation and Fibrosis

Progressive fibrosing interstitial lung diseases (PF-ILDs) result in high mortality and lack effective therapies. The pathogenesis of PF-ILDs involves macrophages driving inflammation and irreversible fibrosis. Fc-γ receptors (FcγRs) regulate macrophages and inflammation, but their roles in PF-ILDs remain unclear. We characterized the expression of FcγRs and found upregulated FcγRIIB in human and mouse lungs after exposure to silica. FcγRIIB deficiency aggravated lung dysfunction, inflammation, and fibrosis in silica-exposed mice. Using single-cell transcriptomics and in vitro experiments, FcγRIIB was found in alveolar macrophages, where it regulated the expression of fibrosis-related genes Spp1 and Ctss. In mice with macrophage-specific overexpression of FcγRIIB and in mice treated with adenovirus by intratracheal instillation to upregulate FcγRIIB, silica-induced functional and histological changes were ameliorated. Our data from three genetic models and a therapeutic model suggest that FcγRIIB plays a protective role that can be enhanced by adenoviral overexpression, representing a potential therapeutic strategy for PF-ILDs.

Co-Administration of Nanowired Monoclonal Antibodies to Inducible Nitric Oxide Synthase and Tumor Necrosis Factor Alpha Together with Antioxidant H-290/51 Reduces SiO2 Nanoparticles-Induced Exacerbation of Pathophysiology of Spinal Cord Trauma

Military personnel are often exposed to silica dust during combat operations across the globe. Exposure to silica dust in US military or service personnel could cause Desert Strom Pneumonitis also referred to as Al Eskan disease causing several organs damage and precipitate autoimmune dysfunction. However, the effects of microfine particles of sand inhalation-induced brain damage on the pathophysiology of traumatic brain or spinal cord injury are not explored. Previously intoxication of silica nanoparticles (50-60 nm size) is shown to exacerbates spinal cord injury induces blood-spinal cord barrier breakdown, edema formation and cellular changes. However, the mechanism of silica nanoparticles-induced cord pathology is still not well known. Spinal cord injury is well known to alter serotonin (5-hydroxytryptamine) metabolism and induce oxidative stress including upregulation of nitric oxide synthase and tumor necrosis factor alpha. This suggests that these agents are involved in the pathophysiology of spinal cord injury. In this review, we examined the effects of combined nanowired delivery of monoclonal antibodies to neuronal nitric oxide synthase (nNOS) together with tumor necrosis factor alpha (TNF-α) antibodies and a potent antioxidant H-290/51 to induce neuroprotection in spinal cord injury associated with silica nanoparticles intoxication. Our results for the first time show that co-administration of nanowired delivery of antibodies to nNOS and TNF-α with H-290/51 significantly attenuated silica nanoparticles-induced exacerbation of spinal cord pathology, not reported earlier.

Therapeutic effect of adipose-derived mesenchymal stem cells (AD-MSCs) compared to pirfenidone on corticosteroid resistance in a mouse model of acute exacerbation of idiopathic pulmonary fibrosis

INTRODUCTION

Acute exacerbation-idiopathic pulmonary fibrosis (AE-IPF) is a life-threatening condition. In the treatment of AE-IPF, corticosteroid medication is commonly utilized. However, there is insufficient evidence to justify its usage. Pirfenidone (PFD) has recently been discovered to be effective in the treatment of AE-IPF patients. However, regenerative therapy, such as stem cell therapy or tissue engineering, is necessary due to ineffective and limited therapies. Combining MSC transplantation with pharmacological therapy may also give additional benefits; nevertheless, its use must be proven experimentally. As a result, the goal of this study was to assess the therapeutic effects of adipose-derived mesenchymal stem cells (AD-MSCs) on corticosteroid resistance in an animal model of AE-IPF caused by bleomycin compared to PFD.

MATERIALS AND METHODS

Seventy C57BL/6J male mice were randomly divided into seven groups, control, BLM, methylprednisolone (MP), PFD, AD-MSCs, PFD +MP, and AD-MSCs +MP.

RESULTS

In terms of survival, collagen deposition, the acute lung injury score (ALI), and the Ashcroft score, AD-MSCs exceeded PFD. AD-MSCs + MP provided protection and preserved the lung's architecture in BLM-induced AE. In addition, AD-MSCs successfully decreased chemokine (CC motif) ligand-2 (CCL2) positive cells and lower pro-fibrotic and pro-inflammatory cytokines.

CONCLUSIONS

AD-MSCs enhanced histological structure, Ashcroft and ALI scores, lung collagen deposition, survival, and cytokines in an animal model of AE-IPF. As a result, we believe that AD-MSCs may be more therapeutically helpful for AE-IPF than presently available therapies, either alone or in conjunction with MP.

Metformin alleviates crystalline silica-induced pulmonary fibrosis by remodeling endothelial cells to mesenchymal transition via autophagy signaling

Silicosis is a severe progressive lung disease without effective treatment methods. Previous evidence has demonstrated that endothelial cell to mesenchymal transition (EndoMT) plays an essential role in pulmonary fibrosis, and pulmonary fibrosis is associated with dysregulation of autophagy, while the relationship between autophagy and EndoMT has not yet been adequately studied. Herein, we established a mouse model of silicosis, and we found that the pharmacological induction of the AMPK/mTOR-dependent pathway using 100 mg/kg Metformin (Met) enhanced autophagy in vivo, and results of the Western blot showed that autophagy-related proteins, LC3 II/I ratio, and Beclin-1 increased while p62 decreased. In addition, Met treatment attenuated silica-induced pulmonary inflammation and decreased collagen deposition by suppressing EndoMT, and the proliferation of human umbilical vein endothelial cells (HUVECs) was also inhibited. Notably, the tube forming assay showed that Met also protected the vascular endothelial cells from silica-induced morphological damage. In conclusion, Met can alleviate inflammatory response and collagen deposition in the process of pulmonary fibrosis induced by silica via suppressing EndoMT through the AMPK/mTOR signaling pathway.

The anti-inflammatory effect of myrrh ethanolic extract in comparison with prednisolone on an autoimmune disease rat model induced by silicate

Autoimmune disease is a complex chronic disease that triggers immune activation against autoantigens resulting in tissue damage. Epidemiological data showed that autoimmune diseases are increasing worldwide over the last decades owing to increased environmental pollution. This study investigates the therapeutic effect of myrrh as a natural medicine compared to prednisolone in the treatment of immune-mediated glomerulonephritis induced by silicate. The autoimmune disease model in rats was induced by injecting 5 mg crystalline sodium silicate suspension subcutaneously once weekly for 20 weeks, and then the rats were treated either with myrrh extract or prednisolone or with both for 6 weeks. Liver and kidney function tests, histopathology, and immunohistochemistry of TNF-α expression in kidney tissue were performed. The creatinine significantly elevated in silica-treated group and decreased in other treated groups. Histopathology of the kidney revealed improvement of glomerular and tubular basement thickness in all treated groups, but the inflammatory cell count slightly decreased in the group treated with myrrh than the other treated groups which showed a marked decrease. TNF-α expression was significantly decreased in all treated groups. Interestingly, the myrrh did not produce hepatic lesions and improve the side effect of prednisolone in the liver when taken in combination. Therefore, myrrh extract possessed anti-inflammatory properties and counteracted the side effect of prednisolone on the liver. Myrrh extract can serve as a conjunctive therapy with prednisolone to treat autoimmune diseases.

Biological effects of crude oil vapor. IV. Cardiovascular effects

Workers in the oil and gas extraction industry are at risk of inhaling volatile organic compounds. Epidemiological studies suggest oil vapor inhalation may affect cardiovascular health. Thus, in this hazard identification study we investigated the effects of inhalation of crude oil vapor (COV) on cardiovascular function. Male rats were exposed to air or COV (300 ppm) for 6 h (acute), or 6 h/day × 4 d/wk. × 4 wk. (sub-chronic). The effects of COV inhalation were assessed 1, 28, and 90 d post-exposure. Acute exposure to COV resulted in reductions in mean arterial and diastolic blood pressures 1 and 28 d after exposure, changes in nitrate-nitrite and H2O2 levels, and in the expression of transcripts and proteins that regulate inflammation, vascular remodeling, and the synthesis of nitric oxide (NO) in the heart and kidneys. The sub-chronic exposure resulted in a reduced sensitivity to α1-adrenoreceptor-mediated vasoconstriction in vitro 28 d post-exposure, and a reduction in oxidative stress in the heart. Sub-chronic COV exposure led to alterations in the expression of NO synthases and anti-oxidant enzymes, which regulate inflammation and oxidative stress in the heart and kidneys. There seems to be a balance between changes in the expression of transcripts associated with the generation of reactive oxygen species (ROS) and antioxidant enzymes. The ability of antioxidant enzymes to reduce or inhibit the effects of ROS may allow the cardiovascular system to adapt to acute COV exposures. However, sub-chronic exposures may result in longer-lasting negative health consequences on the cardiovascular system.

Pulmonary hypertension in patients with pneumoconiosis with progressive massive fibrosis

OBJECTIVES

This study aims to explore the prevalence and clinical features of pulmonary hypertension (PH) in patients with progressive massive fibrosis (PMF) and its correlation with large opacities on CT scans.

METHODS

This retrospective study collected 235 patients with PMF, and 199 were eligible for analysis. The probability of PH development was estimated based on tricuspid regurgitation velocity measured by echocardiogram. The size and the location of large opacities on chest CT were recorded. Potential risk factors for PH secondary to PMF were analysed using regression analysis.

RESULTS

The prevalence of a high or intermediate probability of PH was 39.7% in patients with PMF. Type C of large opacities (OR 6.99, 95% CI 2.34 to 23.00, p<0.001) and central type of the large opacities (OR 8.12, 95% CI 2.89 to 24.71, p<0.001) were identified as the risk factors for PH secondary to PMF. Over a median follow-up of 32.8 months, the survival rate was 73.3% in the PH group, significantly lower than that in the non-PH group (96.6%, p<0.001).

CONCLUSIONS

Over one-third of patients with PMF developed PH. The increased size and the central distribution of large opacities were identified as the risk factors.

Tetrandrine alleviates silicosis by inhibiting canonical and non-canonical NLRP3 inflammasome activation in lung macrophages

Silicosis caused by inhalation of silica particles leads to more than ten thousand new occupational exposure-related deaths yearly. Exacerbating this issue, there are currently few drugs reported to effectively treat silicosis. Tetrandrine is the only drug approved for silicosis treatment in China, and despite more than decades of use, its efficacy and mechanisms of action remain largely unknown. Here, in this study, we established silicosis mouse models to investigate the effectiveness of tetrandrine of early and late therapeutic administration. To this end, we used multiple cardiopulmonary function test, as well as markers for inflammation and fibrosis. Moreover, using single cell RNA sequencing and transcriptomics of lung tissue and quantitative microarray analysis of serum from silicosis and control mice, our results provide a novel description of the target pathways for tetrandrine. Specifically, we found that tetrandrine attenuated silicosis by inhibiting both the canonical and non-canonical NLRP3 inflammasome pathways in lung macrophages. Taken together, our work showed that tetrandrine yielded promising results against silicosis-associated inflammation and fibrosis and further lied the groundwork for understanding its molecular targets. Our results also facilitated the wider adoption and development of tetrandirne, potentially accelerating a globally accepted therapeutic strategy for silicosis.

Trimetazidine, a metabolic modulator, attenuates silica-induced pulmonary fibrosis and decreases lactate levels and LDH activity in rats

Pulmonary fibrosis has been recently linked to metabolic dysregulation. Silica-induced pulmonary fibrosis in rats was employed by the current study to explore the effects of trimetazidine (a metabolic modulator-antianginal drug; TMZ) on silica-induced pulmonary fibrosis. Pulmonary fibrosis was induced by intranasal instillation of silica (50 mg/100 µl/rat) in TMZ versus vehicle-treated rats. Body weights of rats, weights of lungs, and wet-to-dry lung weights were determined. Various parameters were also measured in serum, bronchoalveolar lavage fluid (BALF) in addition to lung tissue homogenates. Moreover, histopathological examination of sectioned lungs for lesion score and distribution and histochemical detection of myeloperoxidase (MPO) in lung tissues were also performed. No significant differences were observed in body weight gains, lung coefficients, lung weights, and wet-to-dry lung weight in silica versus control rats. Elevated lactate levels in serum and lung homogenates were significantly attenuated by TMZ. In addition, lactate dehydrogenase activity, transforming growth factor-β, and total proteins in BALF were significantly normalized with TMZ. Moreover, TMZ significantly increased reduced glutathione and adenosine triphosphate levels and decreased nitrate/nitrite and hydroxyproline content in lungs of silica-treated rats. Histopathological examination of lungs revealed more than 56% reduction in lesion score and distribution by TMZ. MPO expression in lungs of silica-treated rats was also significantly attenuated by TMZ. TMZ attenuates silica-induced pulmonary fibrosis, an effect that could be mediated by suppressing anaerobic glycolysis-induced excessive lactate production. Regulation of oxidative stress could also play a role in TMZ-promoted protective effects.

ZIP12 Contributes to Hypoxic Pulmonary Hypertension by Driving Phenotypic Switching of Pulmonary Artery Smooth Muscle Cells

ABSTRACT

ZIP12, a plasmalemmal zinc transporter, reportedly promotes pulmonary vascular remodeling (PVR) by enhancing proliferation of pulmonary artery smooth muscle cells (PASMCs). However, the mechanisms of ZIP12 facilitating PASMCs proliferation remain incompletely appreciated. It has been acknowledged that proliferation-predisposing phenotypic switching of PASMCs can lead to PVR. Given that hypoxia triggers phenotypic switching of PASMCs and ZIP12 mediates PVR, this study aims to explore whether ZIP12-mediated phenotypic switching of PASMCs contributes to hypoxia-induced PVR. Rats were exposed to hypoxia (10% O2) for 3 weeks to induce PVR, and primary rat PASMCs were cultured under hypoxic condition (3% O2) for 48 hours to induce proliferation. Immunofluorescence, quantitative reverse transcription-polymerase chain reaction, and Western blot analysis were performed to detect the expression of target mRNAs and proteins. EdU incorporation and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay were conducted to measure the proliferation of PASMCs. Hypoxia upregulated ZIP12 expression (both mRNA and protein) in pulmonary arteries and PASMCs. Knockdown of ZIP12 inhibited phenotypic switching of PASMCs induced by hypoxia. We propose that HIF-1α/ZIP12/pERK pathway could represent a novel mechanism underlying hypoxia-induced phenotypic switching of PASMCs. Therapeutic targeting of ZIP12 could be exploited to treat PVR.

Pulmonary hypertension due to silicosis and right upper pulmonary artery occlusion with bronchial anthracofibrosis

Bronchial anthracofibrosis is a rare disease defined as bronchial stenosis with black pigmentation and usually not associated with artery occlusion. The patient was an 81-year-old man with silicosis. He presented with dyspnea on exertion, and pulmonary hypertension due to right upper pulmonary artery occlusion without thromboembolism was diagnosed on the basis of the results of right heart catheterization and pulmonary angiography. Bronchoscopy demonstrated bronchial anthracofibrosis in the right upper lobe. These findings suggested that the cause of PH was silicosis and pulmonary artery occlusion with bronchial anthracofibrosis. He has been treated with home oxygen therapy and tadalafil, and his symptom and 6MWD remain stable.

A suitable silicosis mouse model was constructed by repeated inhalation of silica dust via nose

Silicosis as the serious occupational disease is highly necessary to construct a suitable mouse model for disclosing mechanism of occurrence and development in this disease. Here, the volume-effect relationship and volume-based survival curves in mice who inhaled silica suspension intranasally were analyzed. Notable, the optimal volume 80 μl repeated-inhalation by nose to silica suspension in the inbred mouse C57BL/6 J with the highest susceptibility to silicosis led to a great entrance into the lung and a high survival rate after instillation. After repeated-exposure to 20 mg/mL, 80 μl silica for 16 days and then fed without silica exposure until 31 days, weight of mice showed a trend of first decrease and then recover. Moreover, the degree of pulmonary inflammation and fibrosis in mice were analyzed by pathological and immunohistochemistry staining. Transforming growth factor-beta (TGF-β), smooth muscle alpha-actin (α-SMA) and collagen type-I (collagen I, Col-I) were significantly increased in the silica-exposed mouse lung at post-exposure day 16 compared with the controls. Sirius red stain and Micro-CT analysis showed that lung fibrosis formed at post-exposure day 31. This study highlights the critical importance of perfusion volume and repeated nasal drops in inducing inflammatory response and pulmonary fibrosis in silicosis.

Inhibition of HDAC1 alleviates monocrotaline-induced pulmonary arterial remodeling through up-regulation of miR-34a

Background

It has been found that up-regulation of histone deacetylases 1 (HDAC1) is involved in the development of pulmonary arterial hypertension (PAH). However, it is still unclear whether inhibition of HDAC1 suppresses the development of PAH via restoring miR-34a level in monocrotaline (MCT)-induced PAH rats.

Methods

PAH rat models were induced by intraperitoneal injection of MCT. HDAC1 was suppressed by intraperitoneal injection of the class I HDAC inhibitor MS-275, and miR-34a was over-expressed via tail vein injection of miR-34a agomiR.

Results

HDAC1 protein was significantly increased in MCT-induced PAH rats; this was accompanied with down-regulation of miR-34a and subsequent up-regulation of matrix metalloproteinase 9 (MMP-9)/tissue inhibitor of metalloproteinase 1 (TIMP-1) and MMP-2/TIMP-2. Administration of PAH rats with MS-275 or miR-34a agomiR dramatically abolished MCT-induced reduction of miR-34a and subsequent up-regulation of MMP-9/TIMP-1 and MMP-2/TIMP-2, finally reduced extracellular matrix (ECM) accumulation, pulmonary arterial remodeling, right ventricular systolic pressure (RVSP) and right ventricle hypertrophy index (RVHI) in PAH rats.

Conclusions

HDAC1 contributes to the development of MCT-induced rat PAH by suppressing miR-34a level and subsequently up-regulating the ratio of MMP-9/TIMP-1 and MMP-2/TIMP-2. Inhibition of HDAC1 alleviates pulmonary arterial remodeling and PAH through up-regulation of miR-34a level and subsequent reduction of MMP-9/TIMP-1 and MMP-2/TIMP-2, suggesting that inhibition of HDAC1 might have potential value in the management of PAH.

Histopathological changes of pulmonary vascular remodeling in dogs affected with pulmonary hypertension secondary to degenerative mitral valve disease

INTRODUCTION/OBJECTIVES

Pulmonary hypertension (PH) can cause pulmonary arterial remodeling. Medial remodeling is a structural change of the pulmonary artery seen with PH. Hyperplasia and hypertrophy of pulmonary arterial smooth muscle cells (SMCs) are suggested as causes of medial remodeling. To demonstrate the histopathological changes of the pulmonary artery in dogs affected with PH secondary to degenerative mitral valve disease (DMVD) compared with DMVD without PH and control dogs.

ANIMALS

Lung samples obtained from the carcasses of 19 older small-breed dogs (Control, n = 5; DMVD, n = 7; DMVD + PH, n = 7).

MATERIALS AND METHODS

Lung tissue sections were stained with hematoxylin and eosin, Masson's trichrome, and proliferating cell nuclear antigen (PCNA) immunohistochemistry.

RESULTS

The internal diameters of the pulmonary artery in the three groups were not different. Masson's trichrome staining revealed no collagen deposition in the intimal layer of the pulmonary artery in all dogs. The external diameter, percentage of medial thickness (%MT), percentage of SMC layer and collagen deposition areas, average number of SMCs, and the percentage of PCNA positive cells (%PCNA) of the pulmonary artery were increased in the DMVD and DMVD + PH groups compared with the control group. The %PCNA in the DMVD + PH group was significantly decreased when compared with the DMVD group.

CONCLUSIONS

Medial remodeling was found in left-sided heart failure DMVD dogs with and without PH. The medial remodeling in DMVD dogs with and without PH is related to SMC hyperplasia, hypertrophy, and collagen deposition, leading to an increased medial layer thickness of the pulmonary artery.

Association between Silica Exposure and Cardiovascular Disease Mortality: A Meta-Analysis

Background: Silica exposure is detrimental to health and has, thus, been a global health concern. We performed a systematic review and meta-analysis of existing articles to assess the involvement of silica exposure in cardiovascular disease (CVD) mortality.

Methods: Electronic databases including Web of Sciences, Scopus, PubMed, and Google Scholar were searched for eligible publication until December 2019. The pooled standard mortality ratio (SMR) and the 95% confidence interval (CI) were used to detect the association between silica exposure and CVD mortality.

Results: The pooled estimates of SMR indicated a nonsignificant association between silica exposure and CVD mortality (SMR: 1.26; 95% CI: 0.88-1.63). The subgroup analysis based on the type of CVD indicated a significant positive association between silica exposure and mortality from hypertensive heart disease (SMR: 2.45; 95% CI: 2.16 -2.74) and pulmonary heart disease (SMR: 4.03; 95% CI: 3.87-4.20).

Conclusion: This study confirmed that silica exposure is associated with an enhanced risk of mortality of hypertensive and pulmonary heart diseases. The verification of these results may have important effects on basic preventive strategies for health-care providers. Because of the mismatch in the silica exposure classification, some works in the literature were excluded. Also, the years of silica exposure may be important in CVD mortality. We suggest that these potential confounders be considered in future research.

Factors Associated with Incident Severe Pulmonary Arterial Hypertension in Systemic Autoimmune Rheumatic Diseases: a Nationwide Study

OBJECTIVES

To assess the association of severe pulmonary arterial hypertension (PAH) with particulate matter <2.5 μm (PM2.5) and clinical data in patients with systemic autoimmune rheumatic diseases (SARDs).

METHODS

We used the 2003-2017 nationwide data in Taiwan to identify patients with SARDs, including systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, dermatomyositis/polymyositis and primary Sjögren's syndrome. We identified 479 cases with severe PAH and selected controls matched (1:4) for age, sex, and index-year. We used conditional logistic regression analysis to determine factors associated with risks for severe PAH shown as odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

We found that severe PAH was highly associated with interstitial lung disease (OR, 8.57; 95% CI, 5.52-13.32), congestive heart failure (OR, 7.62; 95% CI, 5.02-11.55), valvular heart disease (OR, 3.34; 95% CI, 2.03-5.50) and slightly associated with thyroid diseases (OR, 1.88; 95% CI, 1.18-3.00), but not the level of exposure to PM2.5. Increased risk for PAH was found in patients receiving corticosteroid (prednisolone equivalent dosage, mg/day, OR, 1.03; 95% CI, 1.01-1.05), biologics (OR, 2.18; 95% CI, 1.15-4.12) as well as immunosuppressants, including cyclosporin (OR, 2.17; 95% CI, 1.31-3.59), azathioprine (OR, 1.96; 95% CI, 1.48-2.61), cyclophosphamide (OR, 2.01; 95% CI, 1.30-3.11) and mycophenolate mofetil/mycophenolic acid (OR, 2.42; 95% CI, 1.37-4.27), and those with the highest level of insured amount (reference, lowest level; OR, 0.53; 95% CI, 0.34-0.83).

CONCLUSION

The population-based study identified risks for severe PAH in patients with SARDs, and these findings provide evidence for PAH risk stratification in patients with SARDs.

The Third Man: DNA sensing as espionage in pulmonary vascular health and disease

For as long as nucleic acids have been utilized to vertically and horizontally transfer genetic material, living organisms have had to develop methods of recognizing cytosolic DNA as either pathogenic (microbial invasion) or physiologic (mitosis and cellular proliferation). Derangement in key signaling molecules involved in these pathways of DNA sensing result in a family of diseases labeled interferonopathies. An interferonopathy, characterized by constitutive expression of type I interferons, ultimately manifests as severe autoimmune disease at a young age. Afflicted patients present with a constellation of immune-mediated conditions, including primary lung manifestations such as pulmonary fibrosis and pulmonary hypertension. The latter condition is especially interesting in light of the known role that DNA damage plays in a variety of types of inherited and induced pulmonary hypertension, with free DNA detection elevated in the circulation of affected individuals. While little is known regarding the role of cytosolic DNA sensing in development of pulmonary vascular disease, exciting new research in the related fields of immunology and oncology potentially sheds light on future areas of fruitful exploration. As such, the goal of this review is to summarize the state of the field of nucleic acid sensing, extrapolating common shared pathways that parallel our knowledge of pulmonary hypertension, in a molecular and cell-specific manner. Principles of DNA sensing related to known pulmonary injury inducing stimuli are also evaluated, in addition to potential therapeutic targets. Finally, future directions in pulmonary hypertension research and treatments will be briefly discussed.

Biological effects of inhaled hydraulic fracturing sand dust. III. Cytotoxicity and pro-inflammatory responses in cultured murine macrophage cells

Cultured murine macrophages (RAW 264.7) were used to investigate the effects of fracking sand dust (FSD) for its pro-inflammatory activity, in order to gain insight into the potential toxicity to workers associated with inhalation of FSD during hydraulic fracturing. While the role of respirable crystalline silica in the development of silicosis is well documented, nothing is known about the toxicity of inhaled FSD. The FSD (FSD 8) used in these studies was from an unconventional gas well drilling site. FSD 8was prepared as a 10 mg/ml stock solution in sterile PBS, vortexed for 15 s, and allowed to sit at room temperature for 30 min before applying the suspension to RAW 264.7cells. Compared to PBS controls, cellular viability was significantly decreased after a 24 h exposure to FSD. Intracellular reactive oxygen species (ROS) production and the production of IL-6, TNFα, and endothelin-1 (ET-1) were up-regulated as a result of the exposure, whereas the hydroxyl radical (.OH) was only detected in an acellular system. Immunofluorescent staining of cells against TNFα revealed that FSD 8 caused cellular blebbing, and engulfment of FSD 8 by macrophages was observed with enhanced dark-field microscopy. The observed changes in cellular viability, cellular morphology, free radical generation and cytokine production all confirm that FSD 8 is cytotoxic to RAW 264.7 cells and warrants future studies into the specific pathways and mechanisms by which these toxicities occur.

Biological effects of inhaled hydraulic fracturing sand dust. VI. Cardiovascular effects

Hydraulic fracturing is used to access oil and natural gas reserves. This process involves the high-pressure injection of fluid to fracture shale. Fracking fluid contains approximately 95% water, chemicals and 4.5% fracking sand. Workers may be exposed to fracking sand dust (FSD) during the manipulation of the sand, and negative health consequences could occur if FSD is inhaled. In the absence of any information about its potential toxicity, a comprehensive rat animal model study (see Fedan et al., 2020) was designed to investigate the bioactivities of several FSDs in comparison to MIN-U-SIL® 5, a respirable α-quartz reference dust used in previous animal models of silicosis, in several organ systems. The goal of this study was to assess the effects of inhalation of one FSD, i.e., FSD 8, on factors and tissues that affect cardiovascular function. Male rats were exposed to 10 or 30 mg/m³ FSD (6 h/d for 4 d) by whole body inhalation, with measurements made 1, 7 or 27 d post-exposure. One day following exposure to 10 mg/m³ FSD the sensitivity to phenylephrine-induced vasoconstriction in tail arteries in vitro was increased. FSD exposure at both doses resulted in decreases in heart rate (HR), HR variability, and blood pressure in vivo. FSD induced changes in hydrogen peroxide concentrations and transcript levels for pro-inflammatory factors in heart tissues. In kidney, expression of proteins indicative of injury and remodeling was reduced after FSD exposure. When analyzed using regression analysis, changes in proteins involved in repair and remodeling were correlated. Thus, it appears that inhalation of FSD does have some prolonged effects on cardiovascular, and, possibly, renal function. The findings also provide information regarding potential mechanisms that may lead to these changes, and biomarkers that could be examined to monitor physiological changes that could be indicative of impending cardiovascular dysfunction.

Pro-inflammatory effects of crystalline- and nano-sized non-crystalline silica particles in a 3D alveolar model

BACKGROUND

Silica nanoparticles (SiNPs) are among the most widely manufactured and used nanoparticles. Concerns about potential health effects of SiNPs have therefore risen. Using a 3D tri-culture model of the alveolar lung barrier we examined effects of exposure to SiNPs (Si10) and crystalline silica (quartz; Min-U-Sil) in the apical compartment consisting of human alveolar epithelial A549 cells and THP-1-derived macrophages, as well as in the basolateral compartment with Ea.hy926 endothelial cells. Inflammation-related responses were measured by ELISA and gene expression.

RESULTS

Exposure to both Si10 and Min-U-Sil induced gene expression and release of CXCL8, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α) and interleukin-1β (IL-1β) in a concentration-dependent manner. Cytokine/chemokine expression and protein levels were highest in the apical compartment. Si10 and Min-U-Sil also induced expression of adhesion molecules ICAM-1 and E-selectin in the apical compartment. In the basolateral endothelial compartment we observed marked, but postponed effects on expression of all these genes, but only at the highest particle concentrations. Geneexpressions of heme oxygenase-1 (HO-1) and the metalloproteases (MMP-1 and MMP-9) were less affected. The IL-1 receptor antagonist (IL-1RA), markedly reduced effects of Si10 and Min-U-Sil exposures on gene expression of cytokines and adhesion molecules, as well as cytokine-release in both compartments.

CONCLUSIONS

Si10 and Min-U-Sil induced gene expression and release of pro-inflammatory cytokines/adhesion molecules at both the epithelial/macrophage and endothelial side of a 3D tri-culture. Responses in the basolateral endothelial cells were only induced at high concentrations, and seemed to be mediated by IL-1α/β released from the apical epithelial cells and macrophages.

Long non-coding RNA CASC2 suppresses pulmonary artery smooth muscle cell proliferation and phenotypic switch in hypoxia-induced pulmonary hypertension

Background

In this study, we aimed to investigate whether and how lncRNA CASC2 was involved in hypoxia-induced pulmonary hypertension (PH)-related vascular remodeling.

Methods

The expression of lncRNAs or mRNAs was detected by qRT-PCR, and western blot analysis or immunochemistry was employed for detecting the protein expression. Cell number assay and EdU (5-ethynyl-2′-deoxyuridine) staining were performed to assess cell proliferation. Besides, flow cytometry and wound healing assay were employed for assessments of cell apoptosis and cell migration, respectively. Rat model of hypoxic PH was established and the hemodynamic measurements were performed. Hematoxylin and eosin (HE) and Masson′s trichrome staining were carried out for pulmonary artery morphometric analysis.

Results

The expression of lncRNA CASC2 was decreased in hypoxia-induced rat pulmonary arterial tissues and pulmonary artery smooth muscle cells (PASMCs). Up-regulation of lncRNA CASC2 inhibited cell proliferation, migration yet enhanced apoptosis in vitro and in vivo in hypoxia-induced PH. Western blot analysis and immunochemistry showed that up-regulation of lncRNA CASC2 greatly decreased the expression of phenotype switch-related marker α-SMA in hypoxia-induced PH. Furthermore, it was indicated by the pulmonary artery morphometric analysis that lncRNA CASC2 suppressed vascular remodeling of hypoxia-induced rat pulmonary arterial tissues.

Conclusion

LncRNA CASC2 inhibited cell proliferation, migration and phenotypic switch of PASMCs to inhibit the vascular remodeling in hypoxia-induced PH.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1018-x) contains supplementary material, which is available to authorized users.

Role of SOD3 in silica-related lung fibrosis and pulmonary vascular remodeling

BACKGROUND

Work-place exposure to silica dust may lead to progressive lung inflammation culminating in the development of silicosis, an irreversible condition that can be complicated by onset of pulmonary hypertension (PH). The molecular mechanisms leading to the development of PH and lung fibrosis in response to silica are not well understood. Oxidant/antioxidant imbalance in the lung may promote fibroproliferation and vascular smooth muscle proliferation, ultimately leading to the development of PH. Herein, we analyze the development of PH and lung fibrosis in mice deficient in extracellular superoxide dismutase (SOD3), an enzyme with anti-oxidant activity.

METHODS

PH and silicosis were induced in wild-type and Sod3-/- mice through intratracheal injection of crystalline silica at dose 0.4 g/kg. Pulmonary hypertension and lung fibrosis were characterized by changes in right ventricular systolic pressure (RVSP) and collagen deposition 28 days following silica injections. Vascular remodeling was analyzed using immunohistochemistry and morphometric analysis. The expression of genes were analyzed using qRT-PCR and Western blot.

RESULTS

C57BL6 mice exposed to silica showed attenuated expression of Sod3 in the lung suggesting a protective role for Sod3. Consistent with this, Sod3-/- mice developed more severe fibrotic inflammatory nodules with increased collagen deposition. Furthermore, the expression of genes involved in tissue remodeling (Timp1), fibrotic lesion formation (Fsp1) and inflammatory response (Mcp1) were significantly elevated in Sod3-/- mice compared to Sod3+/+ mice treated with silica. Infiltration of neutrophils and activated macrophages into affected lung was significantly higher in Sod3 deficient mice. In addition, silica produced more profound effects on elevation of RVSP in Sod3-/- compared to wild-type littermate. Increase in RVSP was concomitant with hypertrophy of pulmonary arteries located in silicotic nodules of both mouse strains, however, vascular remodeling in unaffected areas of lung was detected only in Sod3-/- mice.

CONCLUSIONS

Our data suggest that Sod3 and extracellular oxidative stress may play an important role in the development of pneumoconiosis and pulmonary vascular remodeling following exposure to environmental and occupational silica.

Percutaneous treatment for silicosis-induced pulmonary artery stenosis: A case report and review of the literature

BACKGROUND

Exposure to crystalline silica results in silicosis with initiation and progression of pulmonary fibrosis. The impaired lung parenchyma leads to pulmonary arterial hypertension and increased pressure in the right ventricle of the heart. Usually, the silicosis may be followed by enlargement of hilar lymphnodes, but silicosis-induced pulmonary artery stenosis with severe pulmonary hypertension is rare. Percutaneous pulmonary artery stenting and balloon angioplasty were performed to relieve stenosis and pulmonary hypertension.

METHODS

We report the case of a 52-year-old man who was admitted for persistent dyspnea for 2 years and progressive dyspnea for half a month. He had been a stonemason for 20 years. The computer tomography pulmonary angiography scan images showed partially fibrotic lungs with a disseminated nodular pattern and enlarged bilateral hilar and mediastinal lymphnodes. The echocardiogram and right heart catheterization confirmed the diagnosis of severe pulmonary arterial hypertension.

RESULTS

Pulmonary angiograms showed severe stenosis of the proximal upper right and lower left pulmonary artery. Moderate stenosis occured in a branch of the lower right pulmonary artery and a branch of the upper left pulmonary artery. A total of 2 stents and 4 balloons were used to relieve lesions. The final angiograms showed a significantly increased pulmonary artery caliber. The clinical symptom and 6-minute walk distance of the patient were much improved.

CONCLUSION

To our knowledge, this is the first reported case of percutaneous treatment for silicosis-induced pulmonary artery stenosis and pulmonary hypertension. The clinical symptom, 6-minute walking test, and vessel caliber at areas of stenosis improved significantly following stent implantation and balloon dilatation. However, the patient was followed up for a short period and long-term outcomes have not yet been sufficiently evaluated.

Small interfering RNA against ERK1/2 attenuates cigarette smoke-induced pulmonary vascular remodeling

Cigarette smoke may contribute to pulmonary vascular remodeling (PVR), a result of the proliferation of pulmonary artery smooth muscle cells (PASMCs), before pulmonary hypertension in chronic obstructive pulmonary disease (COPD). Activated extracellular signal-regulated kinases 1 and 2 (ERK1/2) are considered to be involved the process of PVR. This study investigated the potential role of ERK1/2 in the proliferation of rat PASMCs (rPASMCs) and cigarette smoke-induced PVR in rats. A small interfering RNA (siRNA) against ERK1/2 (ERK1/2-siRNA) was synthesized, and it significantly reduced the expression of ERK1/2 and cyclin E1, significantly increased the proportion of cells arrested at G0/G1 phase and significantly suppressed the proliferation of rPASMCs treated with cigarette smoke extract compared with controls (all P<0.05). In rats, ERK1/2-siRNA, which was administered intranasally, also inhibited the activation of ERK1/2 and the upregulation of cyclin E1, both of which were induced after the rats were exposed to cigarette smoke for 3 months. ERK1/2-siRNA also significantly reduced PVR (observed by vessel wall thickness and the proportion of fully muscularized vessels) in cigarette smoke-exposed rats compared with a negative control siRNA (P<0.05). Collectively, these data indicated that ERK1/2-siRNA could attenuate PVR in cigarette smoke-exposed rats, and it may have therapeutic value in the treatment of COPD.

Protective effects of aloperin on monocroline-induced pulmonary hypertension via regulation of Rho A/Rho kinsase pathway in rats

Pulmonary hypertension (PH) is fatal disease which closely involves Rho A/ Rho kinsase (ROCK) pathway. Aloperine is a main active alkaloid extracted from Sophora alopecuroides, which is a traditional Chinese herbal medicine that has been used widely. However, the effects of this alkaloid on pulmonary hypertension and its mechanisms remain unclear. Therefore, this study is designed to investigate whether aloperine has protective effects on PH induced by monocrotaline, whether these effects may be related to regulation of RhoA/ROCK pathway in rats. Pulmonary hypertension was induced by monocrotaline (60mg/kg), and subsequently oral administration of aloperine (25, 50, 100mg/kg/day) for 21 days. At the end of the experiment, rats were underwent hemodynamic and morphologic assessments. At same time, the expression of Rho A, ROCK1, ROCK2, as well as activities of ROCK in the lung of rat has been detected. Afterwards, the expression of p27^kip1, Bax, Bcl-2, which was the downstream proliferation and apoptosis factors of ROCK, were tested. The result indicted that aloperine treatment showed significantly improvement in hemodynamic and pathomorphologic data. Moreover, the reduction in expression of Rho A, ROCK1, ROCK2, and suppression in activities of ROCK were found in rat lungs after aloperine treatment. Furthermore, aloperine also alleviated the MCT-induced changes of p27^kip1, Bax and Bcl-2. In summary, this study indicates that aloperine have protective effects on monocrotaline-induced PH. And these effects may be partially related to RhoA/ROCK pathway. Thus, aloperine could be considered a possible therapeutic strategy for PH.

Role of a novel immune modulating DDR2-expressing population in silica-induced pulmonary fibrosis

Micro-injuries associated with chronic inhaled particle exposures are linked with activation of the immune response and are thought to contribute to progression of fibrotic disease. In the pulmonary environment, we have previously demonstrated a heterogeneous population of circulating fibroblast precursors (CFPs), which are defined by expression of the pan-leukocyte marker CD45 and the collagen receptor, discoidin domain receptor-2 (DDR2). This population is derived from the hematopoietic stem cell, expresses collagen, and has a fibroblastic morphology in vitro. Herein, we demonstrate a novel subset of CFPs expressing immune markers CD11b, CD11c, and major histocompatibility complex II (MHC II). The CFP population was skewed toward this immune marker expressing subset in animals with silica-induced pulmonary fibrosis. Data indicate that this CFP subset upregulates co-stimulatory molecules and MHC II expression in response to silica-induced fibrosis in vivo. Functionally, this population was shown to promote T cell skewing away from a Th1 response and toward a pro-inflammatory profile. These studies represent the first direct flow cytometric and functional evaluation of the novel immune marker expressing CFP subset in an exposure-induced model of pulmonary fibrosis. Elucidating the role of this CFP subset may enhance our understanding of the complex immune balance critical to mediating exposures at the pulmonary-host interface and may be a valuable target for the treatment of exposure-induced pulmonary fibrosis.