Chronic low-grade systemic inflammation causes DNA damage in the lungs of mice

Reduced Bik expression drives low-grade airway inflammation and increased risk for COPD in females

Chronic low-grade inflammation is increasingly recognized as a subtle yet potent risk factor for a multitude of age-related disorders, including respiratory diseases, cardiovascular conditions, metabolic syndromes, autoimmunity, and cancer. In this issue of the JCI, Mebratu, Jones, and colleagues shed new light on the mechanisms that promote low-grade airway inflammation and how this contributes to the development of chronic obstructive pulmonary disease (COPD). Their finding that Bik deficiency leads to spontaneous emphysema in female mice, but not in males, marks a notable advancement in our understanding of how inflammatory processes can diverge based on biological sex. This finding is of clinical relevance, given the vulnerability of women to developing COPD.

Pulmonary function changes in older adults with and without metabolic syndrome

The low-grade inflammation associated with metabolic syndrome (MS) triggers functional and structural alterations in several organs. Whereas lung function impairment is well reported for older adult population, the effect of MS on functional and immunological responses in the lungs remains unclear. In this cross-sectional study we determined whether MS alters pulmonary function, and immunological responses in older adults with MS. The study sample consisted of older adults with MS (68 ± 3 years old; n = 77) and without MS (67 ± 3 years old; n = 77). Impulse oscillometry was used to evaluate airway and tissue resistance, and reactance. Biomarkers of inflammation and fibrosis were assessed in the blood and in breath condensate. The total resistance of the respiratory system (R5Hz; p < 0.009), and the resistance of the proximal (R20Hz; p < 0.001) and distal (R5Hz–R20Hz; p < 0.004) airways were higher in MS individuals compared to those without MS. Pro-inflammatory (leptin, IL-1beta, IL-8, p < 0.001; TNF-alpha, p < 0.04) and anti-inflammatory cytokines (adiponectin, IL-1ra, IL-10, p < 0.001), anti-fibrotic (relaxin 1, relaxin 3, Klotho, p < 0.001) and pro-fibrotic (VEGF, p < 0.001) factors were increased in sera and in breath condensate individuals with MS. The results show that MS adversely affect lung mechanics, function, and immunological response in older adults. The data offer a metabolic basis for the inflammaging of the lungs and suggest the lungs as a potential therapeutic target for controlling the immune response and delaying the onset of impaired lung function in older adults with MS.

PD-L1, FGFR1, PIK3CA, PTEN, and p16 expression in pulmonary emphysema and chronic obstructive pulmonary disease with resected lung squamous cell carcinoma

BACKGROUND

Emphysema and chronic obstructive pulmonary disease (COPD) are well known independent risk factors for lung cancer. However, the developmental mechanisms between emphysema/COPD and lung cancer remain unknown. The purpose of this study was to evaluate PD-L1, FGFR1, PIK3CA, PTEN, and p16 expression in squamous cell carcinoma (SCC) associated with emphysema/COPD.

METHODS

A total of 59 patients with squamous cell lung carcinoma (SCC) resected between 2008 and 2012 were retrospectively reviewed. Emphysema was assessed according to the Goddard score. Total severity was divided into none-mild (0-7), moderate (8-15), and severe (≥ 16). Local severity around the existing tumor was divided into no emphysema (0) and presence of emphysema (1-4). COPD severity was based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. PD-L1, FGFR1, PIK3CA, PTEN, and p16 expression were evaluated by immunohistochemistry (IHC). Expression level was classified as tumor cells (TC) 3 (≥ 50%), TC2 (5-49%), TC1 (1-4%), or TC0 (< 1%), and as tumor-infiltrating immune cells (IC) 3 (≥ 50%), IC2 (5-49%), IC1 (1-4%), or IC0 (< 1%) for PD-L1. Expression level was compared between none-mild/moderate-severe total emphysema, no/presence of local emphysema, no COPD/COPD, and GOLD 1/GOLD 2, 3.

RESULTS

PD-L1 expression was significantly correlated with severity of emphysema in TC0, 1, 2 vs. TC3 (P = 0.012). PD-L1 was significantly higher inversely in none-mild emphysema compared to moderate-severe (95% CI, 0.061-5.852, P = 0.045). There were no other significant associations between PD-L1, FGFR1, PIK3CA, PTEN, and p16 expression and total/local severity of emphysema or presence of COPD/GOLD stage.

CONCLUSIONS

PD-L1 expression in SCC was correlated with severity of emphysema in TC0, 1, 2 vs. TC3 and more frequent in none-mild emphysema than moderate-severe emphysema.

Resveratrol as a potential therapeutic drug for respiratory system diseases

Respiratory system diseases are common and major ailments that seriously endanger human health. Resveratrol, a polyphenolic phytoalexin, is considered an anti-inflammatory, antioxidant, and anticancer agent. Thanks to its wide range of biological activities, resveratrol has become a hotspot in many fields, including respiratory system diseases. Indeed, research has demonstrated that resveratrol is helpful to relieve pulmonary function in the general population. Meanwhile, growing evidence indicates that resveratrol plays a protective role in respiratory system diseases. This review aimed to summarize the main protective effects of resveratrol in respiratory system diseases, including its anti-inflammatory, antiapoptotic, antioxidant, antifibrotic, antihypertensive, and anticancer activities. We found that resveratrol plays a protective role in the respiratory system through a variety of mechanisms, and so it may become a new drug for the treatment of respiratory system diseases.

Resveratrol mitigates lipopolysaccharide-mediated acute inflammation in rats by inhibiting the TLR4/NF-κBp65/MAPKs signaling cascade

Resveratrol (RSV) is a natural compound exhibiting anti-inflammatory effect, but the anti-inflammatory mechanism has not been fully understood. This study is aimed to evaluate the anti-inflammatory activity and mechanism of RSV in lipopolysaccharides-induced rats’ model. The visceral wet/dry weight ratios and the changes of hematologic and biochemical indices indicated that LPS- stimulation mainly caused damages to liver and lung, while pretreatment with RSV could alleviate the lesions. The cytokine assays showed that RSV could markedly decrease the production of proinflammatory mediators and cytokines (IL-1, IL-1β, IL-6, NO, iNOS and COX-2), and increase the expression of anti-inflammatory mediator (IL-10). RSV could inhibit TLR4 signaling pathway by down-regulating the mRNA levels of MyD88 and TRAF6, and suppressing the TLR4 protein. RSV could inhibit the signaling cascades of NF-κBp65 and MAPKs through down-regulating the mRNA levels of IκBα, p38MAPK, JNK, ERK1, ERK2 and ERK5 in liver and lung, and suppressing the dynamic changes of proteins and phosphorylated proteins including IκBα, NF-κBp65, p38MAPK, JNK, ERK1/2 and ERK5 from tissue’s cytoplasm to nucleus. In conclusion, RSV possessed a therapeutic effect on LPS-induced inflammation in rats and the mechanism mainly attributed to suppressing the signaling cascades of NF-κBp65 and MAPKs by inhibiting the TLR4 signaling pathway.

The Gut-Liver-Lung Axis. Modulation of the Innate Immune Response and Its Possible Role in Chronic Obstructive Pulmonary Disease

Evidence from epidemiological studies suggests that a diet high in fiber is associated with better lung function and reduced risk of chronic obstructive pulmonary disease (COPD). The mechanism for this benefit remains unknown, but, as fiber is not absorbed by the gut, this finding suggests that the gut may play an active role in pathogenic pathways underlying COPD. There is a growing awareness that aberrant activity of the innate immune system, characterized by increased neutrophil and macrophage activation, may contribute to the development or progression of COPD. Innate immunity is modulated in large part by the liver, where hepatic cells function in immune surveillance of the portal circulation, as well as providing a rich source of systemic inflammatory cytokines and immune mediators (notably, IL-6 and C-reactive protein). We believe that the beneficial effect of dietary fiber on lung function is through modulation of innate immunity and subsequent attenuation of the pulmonary response to inflammatory stimuli, most apparent in current or former smokers. We propose that the "gut-liver-lung axis" may play a modifying role in the pathogenesis of COPD. In this review, we summarize lines of evidence that include animal models, large prospective observational studies, and clinical trials, supporting the hypothesis that the gut-liver-lung axis plays an integral part in the pathogenic mechanisms underlying the pathogenesis of COPD.

Repeated exposure to 5-bromo-2'-deoxyuridine causes decreased proliferation and low-grade inflammation in the lungs of mice

Incorporation of 5-bromo-2'-deoxyuridine (BrdU) into proliferating cells has been used to label dividing cells in many tissues. Although BrdU has been shown to be genotoxic, teratogenic and mutagenic, such adverse effects have largely been ignored by researchers. We determined whether long-term BrdU exposure causes any histopathological changes in the lungs of mice. Eight-week-old male C57/BL6J mice were administered BrdU by intraperitoneal injection on 3 consecutive days of each week for 14 weeks. While no obvious structural changes such as tissue damage, fibrosis, emphysema, airway remodeling, vascular thickening or tumorigenesis were noted, a moderate degree of macrophage infiltration was observed in the airways and lung parenchyma in the lungs of the mice exposed repeatedly to BrdU (BrdU-exposed mice). The proliferative activities of the airway and alveolar epithelial and mesenchymal cells were reduced in the BrdU-exposed mice, although the numbers of these cells in the lungs were maintained. Double immunofluorescence study of the lungs of the BrdU-exposed mice showed overexpression of IL-6 in the airway epithelial and alveolar wall cells, some of which were also double-positive for BrdU. These results indicate that long-term exposure to BrdU inhibits cell proliferation and induces low-grade inflammation in the lungs of mice. Our findings underscore the need for caution in the interpretation of studies that involve long-term exposure to BrdU.

A review of the Hispanic paradox: time to spill the beans?

Past epidemiological observations and recent molecular studies suggest that chronic obstructive pulmonary disease (COPD) and lung cancer are closely related diseases, resulting from overlapping genetic susceptibility and exposure to aero-pollutants, primarily cigarette smoke. Statistics from the American Lung Association and American Cancer Society reveal that mortality from COPD and lung cancer are lowest in Hispanic subjects and generally highest in African American subjects, with mortality in non-Hispanic white subjects and Asian subjects in between. This observation, described as the “Hispanic paradox”, persists after adjusting for confounding variables, notably smoking exposure and sociodemographic factors. While differences in genetic predisposition might underlie this observation, differences in diet remain a possible explanation. Such a hypothesis is supported by the observation that a diet high in fruit and vegetables has been shown to confer a protective effect on both COPD and lung cancer. In this article, we hypothesise that a diet rich in legumes may explain, in part, the Hispanic paradox, given the traditionally high consumption of legumes (beans and lentils) by Hispanic subjects. Legumes are very high in fibre and have recently been shown to attenuate systemic inflammation significantly, which has previously been linked to susceptibility to COPD and lung cancer in large prospective studies. A similar protective effect could be attributed to the consumption of soy products (from soybeans) in Asian subjects, for whom a lower incidence of COPD and lung cancer has also been reported. This hypothesis requires confirmation in cohort studies and randomised control trials, where the effects of diet on outcomes can be carefully examined in a prospective study design.

Epistemology of the origin of cancer: a new paradigm

Background

Carcinogenesis is widely thought to originate from somatic mutations and an inhibition of growth suppressors, followed by cell proliferation, tissue invasion, and risk of metastasis. Fewer than 10% of all cancers are hereditary; the ratio in gastric (1%), colorectal (3-5%) and breast (8%) cancers is even less. Cancers caused by infection are thought to constitute some 15% of the non-hereditary cancers. Those remaining, 70 to 80%, are called “sporadic,” because they are essentially of unknown etiology. We propose a new paradigm for the origin of the majority of cancers.

Presentation of hypothesis

Our paradigm postulates that cancer originates following a sequence of events that include (1) a pathogenic stimulus (biological or chemical) followed by (2) chronic inflammation, from which develops (3) fibrosis with associated changes in the cellular microenvironment. From these changes a (4) pre-cancerous niche develops, which triggers the deployment of (5) a chronic stress escape strategy, and when this fails to resolve, (6) a transition of a normal cell to a cancer cell occurs. If we are correct, this paradigm would suggest that the majority of the findings in cancer genetics so far reported are either late events or are epiphenomena that occur after the appearance of the pre-cancerous niche.

Testing the hypothesis

If, based on experimental and clinical findings presented here, this hypothesis is plausible, then the majority of findings in the genetics of cancer so far reported in the literature are late events or epiphenomena that could have occurred after the development of a PCN. Our model would make clear the need to establish preventive measures long before a cancer becomes clinically apparent. Future research should focus on the intermediate steps of our proposed sequence of events, which will enhance our understanding of the nature of carcinogenesis. Findings on inflammation and fibrosis would be given their warranted importance, with research in anticancer therapies focusing on suppressing the PCN state with very early intervention to detect and quantify any subclinical inflammatory change and to treat all levels of chronic inflammation and prevent fibrotic changes, and so avoid the transition from a normal cell to a cancer cell.

Implication of the hypothesis

The paradigm proposed here, if proven, spells out a sequence of steps, one or more of which could be interdicted or modulated early in carcinogenesis to prevent or, at a minimum, slow down the progression of many cancers.

IL1- and TGFβ-Nox4 signaling, oxidative stress and DNA damage response are shared features of replicative, oncogene-induced, and drug-induced paracrine 'bystander senescence'

Many cancers arise at sites of infection and inflammation. Cellular senescence, a permanent state of cell cycle arrest that provides a barrier against tumorigenesis, is accompanied by elevated proinflammatory cytokines such as IL1, IL6, IL8 and TNFα. Here we demonstrate that media conditioned by cells undergoing any of the three main forms of senescence, i.e. replicative, oncogene- and drug-induced, contain high levels of IL1, IL6, and TGFb capable of inducing reactive oxygen species (ROS)-mediated DNA damage response (DDR). Persistent cytokine signaling and activated DDR evoke senescence in normal bystander cells, accompanied by activation of the JAK/STAT, TGFβ/SMAD and IL1/NFκB signaling pathways. Whereas inhibition of IL6/STAT signaling had no effect on DDR induction in bystander cells, inhibition of either TGFβ/SMAD or IL1/NFκB pathway resulted in decreased ROS production and reduced DDR in bystander cells. Simultaneous inhibition of both TGFβ/SMAD and IL1/NFκB pathways completely suppressed DDR indicating that IL1 and TGFβ cooperate to induce and/or maintain bystander senescence. Furthermore, the observed IL1- and TGFβ-induced expression of NAPDH oxidase Nox4 indicates a mechanistic link between the senescence-associated secretory phenotype (SASP) and DNA damage signaling as a feature shared by development of all major forms of paracrine bystander senescence.

Future directions: lung aging, inflammation, and human immunodeficiency virus

Chronic lung diseases, including chronic obstructive pulmonary disease (COPD) and pulmonary hypertension (PH), are unusually prevalent among persons infected with human immunodeficiency virus (HIV). Often these disease states are identified at younger ages than would be expected in the general population. Recent epidemiologic, basic scientific, and cross-sectional clinical data have implicated immune dysfunction and cellular senescence as potential drivers of advanced presentations of age-related diseases in HIV-infected persons. This article describes how HIV-associated COPD and PH may fit into a paradigm of immunosenescence, and outlines the hypothesized associations among chronic HIV infection, immune dysfunction and senescence, and cardiopulmonary outcomes.