Compartmental and Temporal Dynamics of Chronic Inflammation and Airway Remodelling in a Chronic Asthma Mouse Model

Background

Allergic asthma is associated with chronic airway inflammation and progressive airway remodelling. However, the dynamics of the development of these features and their spontaneous and pharmacological reversibility are still poorly understood. We have therefore investigated the dynamics of airway remodelling and repair in an experimental asthma model and studied how pharmacological intervention affects these processes.

Methods

Using BALB/c mice, the kinetics of chronic asthma progression and resolution were characterised in absence and presence of inhaled corticosteroid (ICS) treatment. Airway inflammation and remodelling was assessed by the analysis of bronchoalveolar and peribronichal inflammatory cell infiltrate, goblet cell hyperplasia, collagen deposition and smooth muscle thickening.

Results

Chronic allergen exposure resulted in early (goblet cell hyperplasia) and late remodelling (collagen deposition and smooth muscle thickening). After four weeks of allergen cessation eosinophilic inflammation, goblet cell hyperplasia and collagen deposition were resolved, full resolution of lymphocyte inflammation and smooth muscle thickening was only observed after eight weeks. ICS therapy when started before the full establishment of chronic asthma reduced the development of lung inflammation, decreased goblet cell hyperplasia and collagen deposition, but did not affect smooth muscle thickening. These effects of ICS on airway remodelling were maintained for a further four weeks even when therapy was discontinued.

Conclusions

Utilising a chronic model of experimental asthma we have shown that repeated allergen exposure induces reversible airway remodelling and inflammation in mice. Therapeutic intervention with ICS was partially effective in inhibiting the transition from acute to chronic asthma by reducing airway inflammation and remodelling but was ineffective in preventing smooth muscle hypertrophy.     

Evaluation of the BDCA2-DTR Transgenic Mouse Model in Chronic and Acute Inflammation

Background and Aims

Plasmacytoid dendritic cells (pDCs) are a small subset of dendritic cells and the main producers of type I interferons. Besides their contribution to tolerance, they are known to be involved in autoimmune diseases and have recently been implicated in atherosclerosis. However, their precise involvement, particularly in advanced lesion development, remains elusive. Hence, we investigated the role of pDCs in atherogenesis vs atheroprogression by specifically depleting this cell population using the BDCA2-DTR mouse model bred to Apolipoprotein E (Apoe ^-/-) deficient mice.

Methods and Results

Our results revealed that continuous diphtheria toxin-induced pDC depletion in Apoe ^-/- BDCA2-DTR mice receiving a high-fat diet (HFD) for 4 weeks did not alter lesion size or composition. Instead, these mice displayed increased B cell numbers and altered levels of inflammatory cytokines. Analysis of depletion efficiency showed that complete pDC depletion could only be sustained for one week and reoccurring pDCs sorted after 4 weeks did not express DTR anymore. Consequently, we analyzed lesion development in a model of partial carotid ligation, inducing established lesions after 5 weeks of HFD feeding, and only depleted pDCs during the last week of 5 weeks HFD feeding. Despite short-term, but efficient pDC depletion, we observed no differences in atherosclerotic lesion development, but changes in inflammatory cytokine titers. To assure the functionality of the BDCA2-DTR model in acute settings, we additionally examined the effect of pDC depletion in an indirect acute lung injury (iALI) model. This time, efficient pDC depletion resulted in a significantly reduced macrophage and neutrophil accumulation in the lung 12 hours after LPS challenge, underlining a pro-inflammatory role of pDCs in the innate immune response in iALI.

Conclusion

Taken together, the BDCA2-DTR mouse model only allows efficient pDC depletion for one week, which subsequently restricts its usability to more acute but not chronic inflammatory disease models.     

Mechanical Ventilation Drives Inflammation in Severe Viral Bronchiolitis

Introduction

Respiratory insufficiency due to severe respiratory syncytial virus (RSV) infection is the most frequent cause of paediatric intensive care unit admission in infants during the winter season. Previous studies have shown increased levels of inflammatory mediators in airways of mechanically ventilated children compared to spontaneous breathing children with viral bronchiolitis. In this prospective observational multi-center study we aimed to investigate whether this increase was related to disease severity or caused by mechanical ventilation.

Materials and Methods

Nasopharyngeal aspirates were collected <1 hour before intubation and 24 hours later in RSV bronchiolitis patients with respiratory failure (n = 18) and non-ventilated RSV bronchiolitis controls (n = 18). Concentrations of the following cytokines were measured: interleukin (IL)-1α, IL-1β, IL-6, monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-1α.

Results

Baseline cytokine levels were comparable between ventilated and non-ventilated infants. After 24 hours of mechanical ventilation mean cytokine levels, except for MIP-1α, were elevated compared to non-ventilated infected controls: IL-1α (159 versus 4 pg/ml, p<0.01), IL-1β (1068 versus 99 pg/ml, p<0.01), IL-6 (2343 versus 958 pg/ml, p<0.05) and MCP-1 (174 versus 26 pg/ml, p<0.05).

Conclusions

Using pre- and post-intubation observations, this study suggests that endotracheal intubation and subsequent mechanical ventilation cause a robust pulmonary inflammation in infants with RSV bronchiolitis.     

Chronic Prostatic Infection and Inflammation by Propionibacterium acnes in a Rat Prostate Infection Model

Chronic inflammation in the prostate, seen as infiltration of inflammatory cells into the prostate gland in histological samples, affects approximately half the male population without indication of prostate disease, and is almost ubiquitous in patients diagnosed with benign prostate hyperplasia and cancer. Several studies have demonstrated the Gram-positive bacterium Propionibacterium acnes to be frequently present in prostate tissue from men suffering from prostate disease. P. acnes has been shown to be associated with histological inflammation in human prostatectomy specimens, and also to induce strong inflammatory response in prostate-derived tissue culture models. The present paper describes a rat model for assessment of the pathogenic potential of P. acnes in prostate. Prostate glands of Sprague Dawley rats (n = 98) were exposed via an abdominal incision and live P. acnes or, in control rats, saline were injected into the ventral and dorso-lateral lobes. Rats were sacrificed 5 days, 3 weeks, 3 months and 6 months post infection, and prostate tissue was analyzed for bacterial content and histological inflammation. Rat sera were assessed for levels of CRP and anti-P. acnes IgG. Live P. acnes could be recovered from the dorso-lateral lobes up to 3 months post infection, while the ventral lobes were cleared from bacteria at that time. In samples up to 3 months post infection, the dorso-lateral lobes exhibited intense focal inflammation. CRP and IgG levels were elevated throughout the span of the experiment, and reached maximum levels 3 weeks and 3 months post infection, respectively. We show that P. acnes have the potential to cause chronic infection in previously healthy prostate, and that the infection has potential to cause chronic histological inflammation in the infected tissue. The high prevalence of P. acnes in human prostate tissue calls for resolution of pathogenic details. The present rat model suggests that complications such as chronic inflammation may be induced by P. acnes infection.     

肥胖与慢性炎症的研究进展

肥胖常伴随着一系列代谢综合征的发生,肥胖引起的慢性炎症因为与各种代谢综合征的密切联系而成为目前的研究热点。慢性炎症的发生很复杂,涉及多个组织、器官和系统,并且炎症的发生会反过来影响组织的功能。目前针对慢性炎症发生机制的研究结果显示脂肪因子和免疫系统、内质网应激、细胞自噬作用以及内毒素的作用等形成的信号网络参与了慢性炎症的触发和发展。本文就慢性炎症与肥胖关联的几种可能发生机制的最新研究进展作一简要综述。     

Thioredoxin-1 Protects against Neutrophilic Inflammation and Emphysema Progression in a Mouse Model of Chronic Obstructive Pulmonary Disease Exacerbation

Background

Exacerbations of chronic obstructive pulmonary disease (COPD) are characterized by acute enhancement of airway neutrophilic inflammation under oxidative stress and can be involved in emphysema progression. However, pharmacotherapy against the neutrophilic inflammation and emphysema progression associated with exacerbation has not been established. Thioredoxin-1 has anti-oxidative and anti-inflammatory properties and it can ameliorate neutrophilic inflammation through anti-chemotactic effects and prevent cigarette smoke (CS)-induced emphysema. We aimed to determine whether thioredoxin-1 can suppress neutrophilic inflammation and emphysema progression in a mouse model of COPD exacerbation and if so, to reveal the underlying mechanisms.

Results

Mice were exposed to CS and then challenged with polyinosine-polycytidylic acid [poly(I:C)], an agonist for virus-induced innate immunity. Airway neutrophilic inflammation, oxidative stress and lung apoptosis were enhanced in smoke-sensitive C57Bl/6, but not in smoke-resistant NZW mice. Exposure to CS and poly(I:C) challenge accelerated emphysema progression in C57Bl/6 mice. Thioredoxin-1 suppressed neutrophilic inflammation and emphysema progression. Poly(I:C) caused early neutrophilic inflammation through keratinocyte-derived chemokine and granulocyte-macrophage colony-stimulating factor (GM-CSF) release in the lung exposed to CS. Late neutrophilic inflammation was caused by persistent GM-CSF release, which thioredoxin-1 ameliorated. Thioredoxin-1 enhanced pulmonary mRNA expression of MAP kinase phosphatase 1 (MKP-1), and the suppressive effects of thioredoxin-1 on prolonged GM-CSF release and late neutrophilic inflammation disappeared by inhibiting MKP-1.

Conclusion

Using a mouse model of COPD exacerbation, we demonstrated that thioredoxin-1 ameliorated neutrophilic inflammation by suppressing GM-CSF release, which prevented emphysema progression. Our findings deepen understanding of the mechanisms underlying the regulation of neutrophilic inflammation by thioredoxin-1 and indicate that thioredoxin-1 could have potential as a drug to counteract COPD exacerbation.     

General Model of Inflammation

Dysfunctions in the immune system, due to genetics, disease or environmental factors, can cause bacterial colonization and chronic inflammation. In cystic fibrosis and chronic obstructive pulmonary disease, respiratory infections can initiate inflammation of the airway. We propose a system of nonlinear ordinary differential equations to describe interactions between macrophages, both inflammatory and anti-inflammatory cytokines, and bacteria. Small changes in parameters governing inflammatory cytokine production and macrophage sensitivity to cytokines result in dramatically different model behaviors. When the immune system is functioning properly, a non-aggressive pathogen will not provide a sufficient trigger to initiate chronic inflammation, however, in disease positive feedback of the inflammatory cytokine can induce chronic inflammation even after a bacterial infection has been resolved. In addition, if the macrophage population is more sensitive to inflammatory cytokines small perturbations initiated by bacteria will also lead to chronic inflammation. We have found nonaggressive bacteria are able to initiate chronic inflammation and propose why anti-inflammatory cytokine therapy may not be effective in resolving this inflammation.     

LINE1 Derepression in Aged Wild-Type and SIRT6-Deficient Mice Drives Inflammation

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Inflammation and Gli2 Suppress Gastrin Gene Expression in a Murine Model of Antral Hyperplasia

Chronic inflammation in the stomach can lead to gastric cancer. We previously reported that gastrin-deficient (Gast^−/−) mice develop bacterial overgrowth, inflammatory infiltrate, increased Il-1β expression, antral hyperplasia and eventually antral tumors. Since Hedgehog (Hh) signaling is active in gastric cancers but its role in precursor lesions is poorly understood, we examined the role of inflammation and Hh signaling in antral hyperplasia. LacZ reporter mice for Sonic hedgehog (Shh), Gli1, and Gli2 expression bred onto the Gast^−/− background revealed reduced Shh and Gli1 expression in the antra compared to wild type controls (WT). Gli2 expression in the Gast^−/− corpus was unchanged. However in the hyperplastic Gast^−/− antra, Gli2 expression increased in both the mesenchyme and epithelium, whereas expression in WT mice remained exclusively mesenchymal. These observations suggested that Gli2 is differentially regulated in the hyperplastic Gast^−/− antrum versus the corpus and by a Shh ligand-independent mechanism. Moreover, the proinflammatory cytokines Il-1β and Il-11, which promote gastric epithelial proliferation, were increased in the Gast^−/− stomach along with Infγ. To test if inflammation could account for elevated epithelial Gli2 expression in the Gast^−/− antra, the human gastric cell line AGS was treated with IL-1β and was found to increase GLI2 but decrease GLI1 levels. IL-1β also repressed human GAST gene expression. Indeed, GLI2 but not GLI1 or GLI3 expression repressed gastrin luciferase reporter activity by ∼50 percent. Moreover, chromatin immunoprecipitation of GLI2 in AGS cells confirmed that GLI2 directly binds to the GAST promoter. Using a mouse model of constitutively active epithelial GLI2 expression, we found that activated GLI2 repressed Gast expression but induced Il-1β gene expression and proliferation in the gastric antrum, along with a reduction of the number of G-cells. In summary, epithelial Gli2 expression was sufficient to stimulate Il-1β expression, repress Gast gene expression and increase proliferation, leading to antral hyperplasia.     

慢性炎症与动脉粥样硬化关系的研究进展

动脉粥样硬化（atherosclerosis,AS）的发病机制非常复杂,对其研究经历了一个半世纪,直到1999年Ross提出”动脉粥样硬化是一种炎症性疾病”,各种炎症细胞和炎症因子参与动脉粥样硬化的发生和发展过程。已有众多的基础和临床研究都证实炎症在AS中的重要作用,但仍需要对AS发生发展的深入研究,使我们更准确认识和有效的防治AS。本文就近年来慢性炎症与动脉粥样硬化关系的研究进展作一综述。     

Substance P and Chronic Pain in Patients with Chronic Inflammation of Connective Tissue

Objective

Evidence suggests that substance P (SP) is involved in chronic joint inflammation, such as the pathogenesis of rheumatoid arthritis and osteoarthritis. The goal of the research was to evaluate the correlation between chronic pain and changes in the SP level in patients with chronic inflammation of the connective tissue.

Methods

Patients with osteoarthritis and rheumatoid arthritis were enrolled in this study. The relationship between chronic pain intensity and the serum SP concentration was evaluated in these groups of patients with osteoarthritis and rheumatoid arthritis.

Results

The results showed a positive correlation between the serum SP concentrations and chronic pain intensity.

Conclusions

1. The SP serum concentration was significantly different between the groups of patients with OA and RA. 2. There was a positive correlation between the serum SP concentration and chronic pain intensity in OA and RA patients.     

Sedentary Time and Markers of Chronic Low-Grade Inflammation in a High Risk Population

Background

Sedentary behaviour has been identified as a distinct risk factor for several health outcomes. Nevertheless, little research has been conducted into the underlying mechanisms driving these observations. This study aimed to investigate the association of objectively measured sedentary time and breaks in sedentary time with markers of chronic low-grade inflammation and adiposity in a population at a high risk of type 2 diabetes mellitus.

Methods

This study reports data from an ongoing diabetes prevention programme conducted in Leicestershire, UK. High risk individuals were recruited from 10 primary care practices. Sedentary time (<25counts per 15s) was measured using Actigraph GT3X accelerometers (15s epochs). A break was considered as any interruption in sedentary time (≥25counts per 15s). Biochemical outcomes included interleukin-6 (IL-6), C-reactive protein (CRP), leptin, adiponectin and leptin:adiponectin ratio (LAR). A sensitivity analysis investigated whether results were affected by removing participants with a CRP level >10 mg/L, as this can be indicative of acute inflammation.

Results

558 participants (age = 63.6±7.7years; male = 64.7%) had complete adipokine and accelerometer data. Following adjustment for various confounders, sedentary time was detrimentally associated with CRP (β = 0.176±0.057, p = 0.002), IL-6 (β = 0.242±0.056, p = <0.001), leptin (β = 0.146±0.043, p = <0.001) and LAR (β = 0.208±0.052, p = <0.001). Associations were attenuated after further adjustment for moderate-to-vigorous physical activity (MVPA) with only IL-6 (β = 0.231±0.073, p = 0.002) remaining significant; this result was unaffected after further adjustment for body mass index and glycosylated haemoglobin (HbA_1c). Similarly, breaks in sedentary time were significantly inversely associated with IL-6 (β = −0.094±0.047, p = 0.045) and leptin (β = −0.075±0.037, p = 0.039); however, these associations were attenuated after adjustment for accelerometer derived variables. Excluding individuals with a CRP level >10 mg/L consistently attenuated the significant associations across all markers of inflammation.

Conclusion

These novel findings from a high risk population recruited through primary care suggest that sedentary behaviour may influence markers associated with inflammation, independent of MVPA, glycaemia and adiposity.     

MAPK Signaling Drives Inflammation in LPS-Stimulated Cardiomyocytes: The Route of Crosstalk to G-Protein-Coupled Receptors

Profound cardiovascular dysfunction is an important cause of mortality from septic shock. The molecular underpinnings of cardiac dysfunction during the inflammatory surge of early sepsis are not fully understood. MAPKs are important signal transducers mediating inflammation whereas G-protein signaling pathways modulate the cardiac response to stress. Using H9c2 cardiomyocytes, we investigated the interaction of MAPK and G-protein signaling in a sepsis model to test the hypothesis that the cardiomyocyte inflammatory response is controlled by MAPKs via G-protein-mediated events. We found that LPS stimulated proinflammatory cytokine production was markedly exacerbated by siRNA knockdown of the MAPK negative regulator Mkp-1. Cytokine production was blunted when cells were treated with p38 inhibitor. Two important cellular signaling molecules typically regulated by G-protein-coupled receptors, cAMP and PKC activity, were also stimulated by LPS and inflammatory cytokines TNF-α and IL-6, through a process regulated by Mkp-1 and p38. Interestingly, neutralizing antibodies against Gα_s and Gα_q blocked the increase in cellular cAMP and PKC activation, respectively, in response to inflammatory stimuli, indicating a critical role of G-protein coupled receptors in this process. LPS stimulation increased COX-2 in H9c2 cells, which also express prostaglandin receptors. Blockade of G-protein-coupled EP4 prostaglandin receptor by AH 23848 prevented LPS-induced cAMP increase. These data implicate MAPKs and G-proteins in the cardiomyocyte inflammatory response to LPS as well as crosstalk via COX-2-generated PGE₂. These data add to our understanding of the pathogenesis of septic shock and have the potential to guide the selection of future therapeutics.     

Methylprednisolone Stiffens Aortas in Lipopolysaccharide-Induced Chronic Inflammation in Rats

Introduction

Glucocorticoids are commonly used as therapeutic agents in many acute and chronic inflammatory and auto-immune diseases. The current study investigated the effects of methylprednisolone (a synthetic glucocorticoid) on aortic distensibility and vascular resistance in lipopolysaccharide-induced chronic inflammation in male Wistar rats.

Methods

Chronic inflammation was induced by implanting a subcutaneous slow-release ALZET osmotic pump (1 mg kg⁻¹ day⁻¹ lipopolysaccharide) for either 2 or 4 weeks. Arterial wave transit time (τ) was derived to describe the elastic properties of aortas using the impulse response function of the filtered aortic input impedance spectra.

Results

Long-term lipopolysaccharide challenge enhanced the expression of advanced glycation end products (AGEs) in the aortas. Lipopolysaccharide also upregulated the inducible form of nitric oxide synthase to produce high levels of nitric oxide (NO), which resulted in vasodilation, as evidenced by the fall in total peripheral resistance (R_p). However, lipopolysaccharide challenge did not influence the elastic properties of aortas, as shown by the unaltered τ. The NO-mediated vascular relaxation may counterbalance the AGEs-induced arterial stiffening so that the aortic distensibility remained unaltered. Treating lipopolysaccharide-challenged rats with methylprednisolone prevented peripheral vasodilation because of its ability to increase R_p. However, methylprednisolone produced an increase in aorta stiffness, as manifested by the significant decline in τ. The diminished aortic distensibility by methylprednisolone paralleled a significant reduction in NO plasma levels, in the absence of any significant changes in AGEs content.

Conclusion

Methylprednisolone stiffens aortas and elastic arteries in lipopolysaccharide-induced chronic inflammation in rats, for NO activity may be dominant as a counteraction of AGEs.     

Chronic Inflammation Permanently Reshapes Tissue-Resident Immunity in Celiac Disease

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青藤碱对慢性非细菌性大鼠前列腺炎大鼠炎症反应及P38Mapk信号通路的影响

目的:观察青藤碱对慢性非细菌性大鼠前列腺炎大鼠炎症反应及P38Mapk信号通路的影响。方法:将SD大鼠随机分为对照组、青藤碱高、低剂量组。对照组组给予生理盐水灌胃,青藤碱低、中、高剂量组分别给予青藤碱40、80、160mg/kg灌胃,28天后处死。realtime RT-PCR法和western blot法检测肿瘤组织中TNF-、IL-6 mRNA和TNF-、IL-6、p-P38 MAPK蛋白的表达。结果:青藤碱能明显降低慢性非细菌性大鼠前列腺炎大鼠前列腺组织中TNF-、IL-6 mRNA和TNF-、IL-6、p-P38 MAPK蛋白的表达。结论:青藤碱能抑制慢性非细菌性大鼠前列腺炎大鼠前列腺炎症反应,其机制可能与抑制P38 MAP信号通路有关。     

青藤碱对慢性非细菌性大鼠前列腺炎大鼠炎症反应及P38Mapk信号通路的影响

目的：观察青藤碱对慢性非细菌性大鼠前列腺炎大鼠炎症反应及P38Mapk信号通路的影响。方法：将SD大鼠随机分为对照组、青藤碱高、低剂量组。对照组组给予生理盐水灌胃,青藤碱低、中、高剂量组分别给予青藤碱40,80、160mg／kg灌胃,28天后处死。realtimeRT-PCR法和westernblot法检测肿瘤组织中TNF-、IL-6rnR_NA和TNF-、IL-6、P—P38MAPK蛋白的表达。结果：青藤碱能明显降低慢性非细菌性大鼠前列腺炎大鼠前5,1腺组织中TNF-、IL-6mRNA和TNF-、IL-6、p-P38MAPK蛋白的表达。结论：青藤碱能抑制慢性非细菌性大鼠前列腺炎大鼠前列腺炎症反应,其机制可能与抑制P38MAP信号通路有关。