Antimicrobial and Anti-Inflammatory Activity of Apple Polyphenol Phloretin on Respiratory Pathogens Associated With Chronic Obstructive Pulmonary Disease

Bacterial infections contribute to accelerated progression and severity of chronic obstructive pulmonary disease (COPD). Apples have been associated with reduced symptoms of COPD and disease development due to their polyphenolic content. We examined if phloretin, an apple polyphenol, could inhibit bacterial growth and inflammation induced by the main pathogens associated with COPD. Phloretin displayed bacteriostatic and anti-biofilm activity against nontypeable Haemophilus influenzae (NTHi), Moraxella catarrhalis, Streptococcus pneumoniae, and to a lesser extent, Pseudomonas aeruginosa. In vitro, phloretin inhibited NTHi adherence to NCI-H292 cells, a respiratory epithelial cell line. Phloretin also exhibited anti-inflammatory activity in COPD pathogen-induced RAW 264.7 macrophages and human bronchial epithelial cells derived from normal and COPD diseased lungs. In mice, NTHi bacterial load and chemokine (C-X-C motif) ligand 1 (CXCL1), a neutrophil chemoattractant, was attenuated by a diet supplemented with phloretin. Our data suggests that phloretin is a promising antimicrobial and anti-inflammatory nutraceutical for reducing bacterial-induced injury in COPD.

Potential Protective Effects of Equol (Soy Isoflavone Metabolite) on Coronary Heart Diseases-From Molecular Mechanisms to Studies in Humans

Equol, a soy isoflavone-derived metabolite of the gut microbiome, may be the key cardioprotective component of soy isoflavones. Systematic reviews have reported that soy isoflavones have no to very small effects on traditional cardiovascular disease risk factors. However, the potential mechanistic mode of action of equol on non-traditional cardiovascular risk factors has not been systematically reviewed. We searched the PubMed through to July 2021 by using terms for equol and each of the following markers: inflammation, oxidation, endothelial function, vasodilation, atherosclerosis, arterial stiffness, and coronary heart disease. Of the 231 records identified, 69 articles met the inclusion criteria and were summarized. Our review suggests that equol is more lipophilic, bioavailable, and generally more potent compared to soy isoflavones. Cell culture, animal, and human studies show that equol possesses antioxidative, anti-inflammatory, and vasodilatory properties and improves arterial stiffness and atherosclerosis. Many of these actions are mediated through the estrogen receptor β. Overall, equol may have a greater cardioprotective benefit than soy isoflavones. Clinical studies of equol are warranted because equol is available as a dietary supplement.

Sex-dependent acrolein sensitivity in mice is associated with differential lung cell, protein, and transcript changes

Acrolein is a reactive inhalation hazard. Acrolein's initial interaction, which in itself can be function-altering, is followed by time-dependent cascade of complex cellular and pulmonary responses that dictate the severity of the injury. To investigate the pathophysiological progression of sex-dependent acrolein-induced acute lung injury, C57BL/6J mice were exposed for 30 min to sublethal, but toxic, and lethal acrolein. Male mice were more sensitive than female mice. Acrolein of 50 ppm was sublethal to female but lethal to male mice, and 75 ppm was lethal to female mice. Lethal and sublethal acrolein exposure decreased bronchoalveolar lavage (BAL) total cell number at 3 h after exposure. The cell number decrease was followed by progressive total cell and neutrophil number and protein increases. The BAL total cell number in female mice exposed to a sublethal, but not lethal dose, returned to control levels at 16 h. In contrast, BAL protein content and neutrophil number were higher in mice exposed to lethal compared to sublethal acrolein. RNASeq pathway analysis identified greater increased lung neutrophil, glutathione metabolism, oxidative stress responses, and CCL7 (aka MCP-3), CXCL10 (aka IP-10), and IL6 transcripts in males than females, whereas IL10 increased more in female than male mice. Thus, the IL6:IL10 ratio, an indicator of disease severity, was greater in males than females. Further, H3.3 histone B (H3F3B) and pro-platelet basic protein (PPBP aka CXCL7), transcripts increased in acrolein exposed mouse BAL and plasma at 3 h, while H3F3B protein that is associated with neutrophil extracellular traps formation increased at 12 h. These results suggest that H3F3B and PPBP transcripts increase may contribute to extracellular H3F3B and PPBP proteins increase.

First trimester mechanisms of gestational sac placental and foetal teratogenicity: a framework for birth cohort studies

BACKGROUND

The function of the gestational sac (GS) and the placenta in the closely related processes of embryogenesis and teratogenicity in the first trimester has been minimally described. The prevailing assumption is that direct teratogenic effects are mediated by the critical extraembryonic organ, the placenta, which either blocks or transfers exposures to the foetus. Placental transfer is a dominant mechanism, but there are other paradigms by which the placenta can mediate teratogenic effects. Knowledge of these paradigms and first trimester human developmental biology can be useful to the epidemiologist in the conduct of biomarker-based studies of both maternal and child health.

OBJECTIVE AND RATIONALE

Our aim is to provide a causal framework for modelling the teratogenic effects of first trimester exposures on child health outcomes mediated by the GS and placenta using biomarker data collected in the first trimester. We initially present first trimester human developmental biology for the sake of informing and strengthening epidemiologic approaches. We then propose analytic approaches of modelling placental mechanisms by way of causal diagrams using classical non-embryolethal teratogens (diethylstilboestrol [DES], folic acid deficiency and cytomegalovirus [CMV]) as illustrative examples. We extend this framework to two chronic exposures of particular current interest, phthalates and maternal adiposity.

SEARCH METHODS

Information on teratogens was identified by a non-systematic, narrative review. For each teratogen, we included papers that answered the five following questions: (i) why were these exposures declared teratogens? (ii) is there a consensus on biologic mechanism? (iii) is there reported evidence of a placental mechanism? (iv) can we construct a theoretical model of a placental mechanism? and (v) can this knowledge inform future work on measurement and modelling of placental-foetal teratogenesis? We prioritized literature specific to human development, the organogenesis window in the first trimester and non-embryolethal mechanisms.

OUTCOMES

As a result of our review of the literature on five exposures considered harmful in the first trimester, we developed four analytic strategies to address first trimester placental mechanisms in birth cohort studies: placental transfer and direct effects on the foetus (DES and maternal adiposity), indirect effects through targeted placental molecular pathways (DES and phthalates), pre-placental effects through disruptions in embryonic and extraembryonic tissue layer differentiation (folic acid deficiency), and multi-step mechanisms that involve maternal, placental and foetal immune function and inflammation (DES and CMV).

WIDER IMPLICATIONS

The significance of this review is to offer a causal approach to classify the large number of potentially harmful exposures in pregnancy when the exposure occurs in the first trimester. Our review will facilitate future research by advancing knowledge of the first trimester mechanisms necessary for researchers to effectively associate environmental exposures with child health outcomes.

A pathway level analysis of PFAS exposure and risk of gestational diabetes mellitus

Per- and polyfluoroalkyl substances (PFAS) have been found to be associated with gestational diabetes mellitus (GDM) development, a maternal health disorder in pregnancy with negative effects that can extend beyond pregnancy. Studies that report on this association are difficult to summarize due to weak associations and wide confidence intervals. One way to advance this field is to sharpen the biologic theory on a causal pathway behind this association, and to measure it directly by way of molecular biomarkers. The aim of this review is to summarize the literature that supports a novel pathway between PFAS exposure and GDM development. Epidemiological studies demonstrate a clear association of biomarkers of thyroid hormones and glucose metabolism with GDM development. We report biologic plausibility and epidemiologic evidence that PFAS dysregulation of maternal thyroid hormones and thyrotropin (TSH) may disrupt glucose homeostasis, increasing the risk of GDM. Overall, epidemiological studies demonstrate that PFAS were positively associated with TSH and negatively with triiodothyronine (T3) and thyroxine (T4). PFAS were generally positively associated with glucose and insulin levels in pregnancy. We propose dysregulation of thyroid function and glucose metabolism may be a critical and missing component in the accurate estimation of PFAS on the risk of GDM.

Phloretin, an Apple Polyphenol, Inhibits Pathogen-Induced Mucin Overproduction

SCOPE

Bacterial infection induces mucus overproduction, contributing to acute exacerbations and lung function decline in chronic respiratory diseases. A diet enriched in apples may provide protection from pulmonary disease development and progression. This study examined whether phloretin, an apple polyphenol, inhibits mucus synthesis and secretion induced by the predominant bacteria associated with chronic respiratory diseases.

METHODS AND RESULTS

The expression of mucus constituent mucin 5AC (MUC5AC) in FVB/NJ mice and NCI-H292 epithelial cells is analyzed. Nontypeable Haemophilus influenzae (NTHi)-infected mice developed increased MUC5AC mRNA, which a diet containing phloretin inhibited. In NCI-H292 cells, NTHi, Moraxella catarrhalis, Streptococcus pneumoniae, and Pseudomonas aeruginosa increased MUC5AC mRNA, which phloretin inhibited. Phloretin also diminished NTHi-induced MUC5AC protein secretion. NTHi-induced increased MUC5AC required toll-like receptor 4 (TLR4) and NADH oxidase 4 (NOX4) signaling and subsequent activation of the epidermal growth factor receptor (EGFR)/mitogen-activated protein kinase (MAPK) pathway. Phloretin inhibited NTHi-induced TLR4/NOX4 and EGFR/MAPK signaling, thereby preventing increased MUC5AC mRNA. EGFR activation can also result from increased EGFR ligand synthesis and subsequent ligand activation by matrix metalloproteinases (MMPs). In NCI-H292 cells, NTHi increased EGFR ligand and MMP1 and MMP13 mRNA, which phloretin inhibited.

CONCLUSIONS

In summary, phloretin is a promising therapeutic candidate for preventing bacterial-induced mucus overproduction.

A toolkit for the application of placental-fetal molecular biomarkers in epidemiologic studies of the fetal origins of chronic disease

Purpose of review

In this review, we provide essential background knowledge and an analytical framework for the application of placental-fetal molecular biomarkers in fetal origins chronic disease epidemiology. The widely available and highly quantitative placental hormone human chorionic gonadotropin (hCG) is used as an example. hCG is currently used for diagnosing fetal genetic disorders; yet it can and should be expanded to understanding the fetal origins of chronic diseases. We provide justification and methods to do this.

Recent findings

Ten papers published in the last 5 years were identified with supportive findings relevant to the application of biomarkers of hCG in epidemiologic studies on the developmental origins of health and disease (DOHaD).

Summary

There is increasing and consistent evidence that placental-fetal biomarkers may be highly informative in observational studies, as exemplified by hCG, with the correct approaches for measurement and data analysis.

Albumin Protects Lung Cells against Acrolein Cytotoxicity and Acrolein-Adducted Albumin Increases Heme Oxygenase 1 Transcripts

Albumin is an abundant protein in the lung lining fluid that forms an interface between lung epithelial cells and the external environment. In the lung, albumin can be targeted for adduction by inhaled acrolein. Acrolein, an α,β-unsaturated aldehyde, reacts with biomolecules via Michael addition at the β-carbon or Schiff base formation at the carbonyl carbon. To gain insight into acrolein's mode of action, we investigated in vitro albumin-acrolein reactivity and the consequence of albumin adduction by acrolein on cytotoxicity and transcript changes in NCI-H441 and human airway epithelial cells (HAEC). Albumin protected NCI-H441 cells from acrolein toxicity. In addition, albumin inhibited acrolein-induced increase of transcripts associated with cellular stress response, activating transcription factor 3 (ATF3), and antioxidant response, heme oxygenase 1 (HMOX1) in HAEC cells. Acrolein-adducted albumin itself increased HMOX1 transcripts but not ATF3 transcripts. The HMOX1 transcript increase was inhibited by hydralazine, a carbonyl scavenger, suggesting that the carbonyl group of acrolein-adducted albumin mediated HMOX1 transcript increase. In acutely exposed C57BL/6J mice, bronchoalveolar lavage protein carbonylation increased. Acrolein-adducted albumin Cys34 was identified by nLC-MS/MS. These findings indicate that adduction of albumin by acrolein confers a cytoprotective function by scavenging free acrolein, decreasing a cellular stress response, and inducing an antioxidant gene response. Further, these results suggest that β-carbon reactivity may be required for acrolein's cytotoxicity and ATF3 transcript increase, and the carbonyl group of acrolein-adducted albumin can induce HMOX1 transcript increase.

Effects of soy isoflavones on cognitive function: a systematic review and meta-analysis of randomized controlled trials

CONTEXT

The results of preclinical and observational studies support the beneficial effect of soy isoflavones on cognition.

OBJECTIVE

This review aimed to evaluate the effects of soy isoflavones on cognition in adults.

DATA SOURCES

The PUBMED, EMBASE, Ovid Medline, Cochrane Library, and clinicaltrials.gov databases were searched.

STUDY SELECTION

Two researchers independently screened 1955 records, using the PICOS criteria: participants were adults; intervention was dietary sources with soy isoflavones or isolated soy isoflavones; comparator was any comparator; outcome was cognitive function; study type was randomized controlled trials (RCTs). A third researcher was consulted to resolve any discrepancies. Sixteen RCTs were included and their quality assessed.

DATA EXTRACTION

Information on study design, characteristics of participants, and outcomes was extracted. PRISMA guidelines were followed.

DATA ANALYSIS

A random-effects meta-analysis was used to pool estimates across studies. In the 16 RCTs (1386 participants, mean age = 60 y), soy isoflavones were found to improve overall cognitive function (standardized mean difference [SMD], 0.19; 95% confidence interval [CI], 0.07-0.32) and memory (SMD, 0.15; 95%CI, 0.03-0.26).

CONCLUSION

The results showed that soy isoflavones may improve cognitive function in adults.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42018082070.

The impact of equol-producing status in modifying the effect of soya isoflavones on risk factors for CHD: a systematic review of randomised controlled trials

Recent studies suggest that the ability to produce equol, a metabolite of the soya isoflavone daidzein, is beneficial to coronary health. Equol, generated by bacterial action on isoflavones in the human gut, is biologically more potent than dietary sources of isoflavones. Not all humans are equol producers. We investigated whether equol-producing status is favourably associated with risk factors for CHD following an intervention by dietary soya isoflavones. We systematically reviewed randomised controlled trials (RCT) that evaluated the effect of soya isoflavones on risk factors for CHD and that reported equol-producing status. We searched PubMed, EMBASE, Ovid Medline and the Cochrane Central Register for Controlled Trials published up to April 2015 and hand-searched bibliographies to identify the RCT. Characteristics of participants and outcomes measurements were extracted and qualitatively analysed. From a total of 1671 studies, we identified forty-two articles that satisfied our search criteria. The effects of equol on risk factors for CHD were mainly based on secondary analyses in these studies, thus with inadequate statistical power. Although fourteen out of the forty-two studies found that equol production after a soya isoflavone intervention significantly improved a range of risk factors including cholesterol and other lipids, inflammation and blood pressure variables, these results need further verification by sufficiently powered studies. The other twenty-eight studies primarily reported null results. RCT of equol, which has recently become available as a dietary supplement, on CHD and its risk factors are awaited.

Novel PDE4 inhibitors derived from Chinese medicine forsythia

Cyclic adenosine monophosphate (cAMP) is a crucial intracellular second messenger molecule that converts extracellular molecules to intracellular signal transduction pathways generating cell- and stimulus-specific effects. Importantly, specific phosphodiesterase (PDE) subtypes control the amplitude and duration of cAMP-induced physiological processes and are therefore a prominent pharmacological target currently used in a variety of fields. Here we tested the extracts from traditional Chinese medicine, Forsythia suspense seeds, which have been used for more than 2000 years to relieve respiratory symptoms. Using structural-functional analysis we found its major lignin, Forsynthin, acted as an immunosuppressant by inhibiting PDE4 in inflammatory and immune cell. Moreover, several novel, selective small molecule derivatives of Forsythin were tested in vitro and in murine models of viral and bacterial pneumonia, sepsis and cytokine-driven systemic inflammation. Thus, pharmacological targeting of PDE4 may be a promising strategy for immune-related disorders characterized by amplified host inflammatory response.

Pathogenic mechanism of second hand smoke induced inflammation and COPD

Second hand smoke (SHS) introduces thousands of toxic chemicals into the lung, including carcinogens and oxidants, which cause direct airway epithelium tissue destruction. It can also illicit indirect damage through its effect on signaling pathways related to tissue cell repair and by the abnormal induction of inflammation into the lung. After repeated exposure to SHS, these symptoms can lead to the development of pulmonary inflammatory disorders, including chronic obstructive pulmonary disease (COPD). COPD is a severe pulmonary disease characterized by chronic inflammation and irreversible tissue destruction. There is no causal cure, as the mechanism behind the development and progression of the disease is still unknown. Recent discoveries implicate genetic predisposition associated with inflammatory response contributed to the development of COPD, linked to irregular innate and adaptive immunity, as well as a risk factor for cancer. The use of animal models for both cigarette smoke (CS) and SHS associated in vivo experiments has been crucial in elucidating the pathogenic mechanisms and genetic components involved in inflammation-related development of COPD.