Flavones induce neutrophil apoptosis by down-regulation of Mcl-1 via a proteasomal-dependent pathway

What can we learn about fish neutrophil and macrophage response to immune challenge from studies in zebrafish

Fish rely, to a high degree, on the innate immune system to protect them against the constant exposure to potential pathogenic invasion from the surrounding water during homeostasis and injury. Zebrafish larvae have emerged as an outstanding model organism for immunity. The cellular component of zebrafish innate immunity is similar to the mammalian innate immune system and has a high degree of sophistication due to the needs of living in an aquatic environment from early embryonic stages of life. Innate immune cells (leukocytes), including neutrophils and macrophages, have major roles in protecting zebrafish against pathogens, as well as being essential for proper wound healing and regeneration. Zebrafish larvae are visually transparent, with unprecedented in vivo microscopy opportunities that, in combination with transgenic immune reporter lines, have permitted visualisation of the functions of these cells when zebrafish are exposed to bacterial, viral and parasitic infections, as well as during injury and healing. Recent findings indicate that leukocytes are even more complex than previously anticipated and are essential for inflammation, infection control, and subsequent wound healing and regeneration.

Euphorbia hirta nanoextract as a piezoelectric ultrasonic scaler coolant in gingivitis treatment in a Wistar rat model

Objectives

This research was aimed at investigating the effects of various concentrations of Euphorbia hirta nanoextract as a piezoelectric scaler coolant on gingivitis healing in a Wistar rat model.

Methods

A piezoelectric ultrasonic scaler coolant was made from E. hirta nanoextract through ionic gelation. Experiments were conducted in 45 adult male Wistar rats divided into three groups treated with E. hirta nanoextract coolant (25%, 30%, and 35% concentrations), and negative and positive control groups. A silk ligature was used to trap debris and induce gingivitis in the maxillary incisors of the rats. Scaling was conducted with a piezoelectric ultrasonic scaler after the respective treatment for each group. Data were collected on days 3, 5, 7, 14, and 21 after treatment. Observations were collected with an Optilab® camera at 400× magnification. Angiogenesis and neutrophil data were analyzed with two-way analysis of variance (ANOVA) and post hoc Duncan tests at a 95% significance level.

Results

Use of E. hirta nanoextract as a piezoelectric ultrasonic coolant accelerated gingivitis healing in Wistar rats, particularly at a 25% concentration. Two-way ANOVA indicated a significant difference in angiogenesis and neutrophil counts between the control group and each treatment group (p < 0.05). Duncan's post-hoc test showed significant differences in mean neutrophil numbers and angiogenesis among groups on days 3, 5, 7, 14, and 21. The group treated with 25% nanoextract concentration showed no significant differences with respect to the positive control group.

Conclusions

Use of E. hirta nanoextract as a piezoelectric ultrasonic coolant had good therapeutic results in promoting gingivitis healing. E. hirta nanoextract may potentially resolve inflammation in gingivitis by modulating neutrophils and angiogenesis.

Research progress of Traditional Chinese Medicine (TCM) in targeting inflammation and lipid metabolism disorder for arteriosclerosis intervention: A review

Atherosclerosis (AS) is a chronic disease caused by inflammation and lipid deposition. Immune cells are extensively activated in the lesions, producing excessive pro-inflammatory cytokines, which accompany the entire pathological process of AS. In addition, the accumulation of lipid-mediated lipoproteins under the arterial intima is a crucial event in the development of AS, leading to vascular inflammation. Improving lipid metabolism disorders and inhibiting inflammatory reactions are the primary treatment methods currently used in medical practice to delay AS progression. With the development of traditional Chinese medicine (TCM), more mechanisms of action of the monomer of TCM, Chinese patent medicine, and compound prescription have been studied and explored. Research has shown that some Chinese medicines can participate in treating AS by targeting and improving lipid metabolism disorders and inhibiting inflammatory reactions. This review explores the research on Chinese herbal monomers, compound Chinese medicines, and formulae that improve lipid metabolism disorders and inhibit inflammatory reactions to provide new supplements for treating AS.

Inflammation and Obesity: The Pharmacological Role of Flavonoids in the Zebrafish Model

A Mediterranean-style diet is highly encouraged thanks to its healthy food pattern, which includes valuable nutraceuticals such as polyphenols. Among these, flavonoids are associated with relevant biological properties through which they prevent or fight the onset of several human pathologies. Globally, the enhanced incidence of overweight and obese people has caused a dramatic increase in comorbidities, raising the need to provide better therapies. Therefore, the development of sophisticated animal models of metabolic dysregulation has allowed for a deepening of knowledge on this subject. Recent advances in using zebrafish (Danio rerio) as model for metabolic disease have yielded fundamental insights into the potential anti-obesity effects of flavonoids. Chronic low-grade inflammation and immune system activation seem to characterize the pathogenesis of obesity; thus, their reduction might improve the lipid profile of obese patients or prevent the development of associated metabolic illnesses. In this review, we highlight the beneficial role of flavonoids on obesity and related diseases linked to their anti-inflammatory properties. In light of the summarized studies, we suggest that anti-inflammatory therapies could have a relevant place in the prevention and treatment of obesity and metabolic disorders.

A retrospective study of Pupingqinghua prescription versus Lianhuaqingwen in Chinese participants infected with SARS-CoV-2 Omicron variants

Background: Coronavirus disease (COVID-19) seriously endangers global public health. Pupingqinghua prescription (PPQH) is an herbal formula from traditional Chinese medicine used for treatment of SARS-CoV-2 infection. This study aims to evaluate the clinical efficacy and safety of PPQH in Chinese participants infected with the SARS-CoV-2 Omicron variant. Methods: A total of 873 SARS-CoV-2 (Omicron)-infected patients were included. Among them, the patients were divided into the PPQH group (653 cases) and LHQW group (220 cases) according to different medications. The effectiveness indicators (hematological indicators, Ct values of novel Coronavirus nucleic acid tests, and viral load-shedding time) and safety indicators (liver and kidney function and adverse events) were analyzed. Results: There was no significant difference in baseline characteristics between the PPQH group and the LHQW group, except the gender; After the treatment, the levels of IL-5, IL-6, IL-10, NK cells, and INF-α of the patients in the PPQH group showed a downward trend (p < 0.05); The viral load shedding time was 5.0 (5.0, 7.0) in the PPQH group and 5.0 (4.0, 7.0) in the LHQW group; both PPQH and LHQW can shorten the duration of symptoms of fever, cough, and sore throat. The re-positive rate of COVID-19 test was 1.5 % in the PPQH group and 2.3 % in the LHQW group. In terms of safety, the levels of γ-GTT decreased significantly (p < 0.01); gastrointestinal reaction was the primary adverse reaction, and the reaction rate was 4.7 % in the PPQH group and 9.5 % in the LHQW group. Conclusion: PPQH can shorten the length of hospital stay and improve clinical symptoms of patients with SARS-COV-2 (Omicron), and it also has a good safety profile.

Insights into the Pharmacological Effects of Flavonoids: The Systematic Review of Computer Modeling

Computer modeling is a method that is widely used in scientific investigations to predict the biological activity, toxicity, pharmacokinetics, and synthesis strategy of compounds based on the structure of the molecule. This work is a systematic review of articles performed in accordance with the recommendations of PRISMA and contains information on computer modeling of the interaction of classical flavonoids with different biological targets. The review of used computational approaches is presented. Furthermore, the affinities of flavonoids to different targets that are associated with the infection, cardiovascular, and oncological diseases are discussed. Additionally, the methodology of bias risks in molecular docking research based on principles of evidentiary medicine was suggested and discussed. Based on this data, the most active groups of flavonoids and lead compounds for different targets were determined. It was concluded that flavonoids are a promising object for drug development and further research of pharmacology by in vitro, ex vivo, and in vivo models is required.

Transgenic zebrafish larvae as a non-rodent alternative model to assess pro-inflammatory (neutrophil) responses to nanomaterials

Hazard studies for nanomaterials (NMs) commonly assess whether they activate an inflammatory response. Such assessments often rely on rodents, but alternative models are needed to support the implementation of the 3Rs principles. Zebrafish (Danio rerio) offer a viable alternative for screening NM toxicity by investigating inflammatory responses. Here, we used non-protected life stages of transgenic zebrafish (Tg(mpx:GFP)ⁱ¹¹⁴) with fluorescently-labeled neutrophils to assess inflammatory responses to silver (Ag) and zinc oxide (ZnO) NMs using two approaches. Zebrafish were exposed to NMs via water following a tail fin injury, or NMs were microinjected into the otic vesicle. Zebrafish were exposed to NMs at 3 days post-fertilization (dpf) and neutrophil accumulation at the injury or injection site was quantified at 0, 4, 6, 8, 24, and 48 h post-exposure. Zebrafish larvae were also exposed to fMLF, LTB₄, CXCL-8, C5a, and LPS to identify a suitable positive control for inflammation induction. Aqueous exposure to Ag and ZnO NMs stimulated an enhanced and sustained neutrophilic inflammatory response in injured zebrafish larvae, with a greater response observed for Ag NMs. Following microinjection, Ag NMs stimulated a time-dependent neutrophil accumulation in the otic vesicle which peaked at 48 h. LTB₄ was identified as a positive control for studies investigating inflammatory responses in injured zebrafish following aqueous exposure, and CXCL-8 for microinjection studies that assess responses in the otic vesicle. Our findings support the use of transgenic zebrafish to rapidly screen the pro-inflammatory effects of NMs, with potential for wider application in assessing chemical safety (e.g. pharmaceuticals).

Biomaterial and cellular implants:foreign surfaces where immunity and coagulation meet

Exposure of blood to a foreign surface in the form of a diagnostic or therapeutic biomaterial device or implanted cells or tissues, elicits an immediate, evolutionarily conserved thrombo-inflammatory response by the host. Primarily designed to protect against invading organisms following an injury, this innate response features instantaneous activation of several blood-borne, highly interactive and well-orchestrated cascades and cellular events that limit bleeding, destroy and eliminate the foreign substance/cells, and promote healing and a return to homeostasis via delicately balanced regenerative processes. In the setting of blood-contacting synthetic or natural biomaterials and implantation of foreign cells/tissues, innate responses are robust, albeit highly context-specific. Unfortunately, they tend to be less than adequately regulated by the host's natural anti-coagulant/anti-inflammatory pathways, thereby jeopardizing the functional integrity of the device, as well as the health of the host. Strategies to achieve biocompatibility with a sustained return to homeostasis, particularly while the device remains in situ and functional, continue to elude scientists and clinicians. In this review, some of the complex mechanisms by which biomaterials and cellular transplants provide a "hub" for activation and amplification of coagulation and immunity - thrombo-inflammation - will be discussed, with a view toward the development of innovative means of overcoming the innate challenges.

Zebrafish as a Useful Model to Study Oxidative Stress-Linked Disorders: Focus on Flavonoids

The zebrafish is considered one of the most versatile experimental animal models. The transparency of the embryos, the small size, the rapid development and the homology with higher vertebrates have made the zebrafish a valuable model also for drug screening. Its use is closely related for the determination of bioactivity, toxicity and off-target side effects of novel drug candidates, which also allows a thorough evaluation of new targets; thus, it may represent a suitable model for drug screening and the optimization of novel candidates. Flavonoids are polyphenolic compounds widely present in fruits, vegetables and cereals. Polyphenols are important for both plants and humans, considering their involvement in defense mechanisms, particularly against oxidative stress. They protect plants from biotic and abiotic stressors and prevent or treat oxidative-based human diseases. For these reasons, polyphenols are used as nutraceuticals, functional foods and supplements by the pharmaceutical industry. Therefore, the most relevant findings on zebrafish as a useful experimental model to study oxidative stress-linked disorders, focusing on the biological activities of flavonoids, are here summarized and reviewed.

Mcl-1 protects eosinophils from apoptosis and exacerbates allergic airway inflammation

Eosinophils are key effector cells in allergic diseases. Here we investigated Mcl-1 (an anti-apoptotic protein) in experimental allergic airway inflammation using transgenic overexpressing human Mcl-1 mice (hMcl-1) and reducing Mcl-1 by a cyclin-dependent kinase inhibitor. Overexpression of Mcl-1 exacerbated allergic airway inflammation, with increased bronchoalveolar lavage fluid cellularity, eosinophil numbers and total protein, and an increase in airway mucus production. Eosinophil apoptosis was suppressed by Mcl-1 overexpression, with this resistance to apoptosis attenuated by cyclin-dependent kinase inhibition which also rescued Mcl-1-exacerbated allergic airway inflammation. We propose that targeting Mcl-1 may be beneficial in treatment of allergic airway disease.

Therapeutic Potential of Flavonoids in Pain and Inflammation: Mechanisms of Action, Pre-Clinical and Clinical Data, and Pharmaceutical Development

Pathological pain can be initiated after inflammation and/or peripheral nerve injury. It is a consequence of the pathological functioning of the nervous system rather than only a symptom. In fact, pain is a significant social, health, and economic burden worldwide. Flavonoids are plant derivative compounds easily found in several fruits and vegetables and consumed in the daily food intake. Flavonoids vary in terms of classes, and while structurally unique, they share a basic structure formed by three rings, known as the flavan nucleus. Structural differences can be found in the pattern of substitution in one of these rings. The hydroxyl group (-OH) position in one of the rings determines the mechanisms of action of the flavonoids and reveals a complex multifunctional activity. Flavonoids have been widely used for their antioxidant, analgesic, and anti-inflammatory effects along with safe preclinical and clinical profiles. In this review, we discuss the preclinical and clinical evidence on the analgesic and anti-inflammatory proprieties of flavonoids. We also focus on how the development of formulations containing flavonoids, along with the understanding of their structure-activity relationship, can be harnessed to identify novel flavonoid-based therapies to treat pathological pain and inflammation.

Neutrophils restrain allergic airway inflammation by limiting ILC2 function and monocyte-dendritic cell antigen presentation

Neutrophil mobilization, recruitment, and clearance must be tightly regulated as overexuberant neutrophilic inflammation is implicated in the pathology of chronic diseases, including asthma. Efforts to target neutrophils therapeutically have failed to consider their pleiotropic functions and the implications of disrupting fundamental regulatory pathways that govern their turnover during homeostasis and inflammation. Using the house dust mite (HDM) model of allergic airway disease, we demonstrate that neutrophil depletion unexpectedly resulted in exacerbated T helper 2 (TH2) inflammation, epithelial remodeling, and airway resistance. Mechanistically, this was attributable to a marked increase in systemic granulocyte colony-stimulating factor (G-CSF) concentrations, which are ordinarily negatively regulated in the periphery by transmigrated lung neutrophils. Intriguingly, we found that increased G-CSF augmented allergic sensitization in HDM-exposed animals by directly acting on airway type 2 innate lymphoid cells (ILC2s) to elicit cytokine production. Moreover, increased systemic G-CSF promoted expansion of bone marrow monocyte progenitor populations, which resulted in enhanced antigen presentation by an augmented peripheral monocyte-derived dendritic cell pool. By modeling the effects of neutrophil depletion, our studies have uncovered previously unappreciated roles for G-CSF in modulating ILC2 function and antigen presentation. More broadly, they highlight an unexpected regulatory role for neutrophils in limiting TH2 allergic airway inflammation.

Blood Neutrophils Are Reprogrammed in Bronchiectasis

RATIONALE

Excessive neutrophilic airway inflammation is the central feature of bronchiectasis, but little is known about neutrophils in bronchiectasis.

OBJECTIVES

To assess blood neutrophil phenotype in patients with bronchiectasis while stable and during exacerbations.

METHODS

In the clinically stable arm of this study, there were eight healthy volunteers, eight patients with mild bronchiectasis, and eight patients with severe bronchiectasis. In addition, six patients with severe bronchiectasis were compared with six patients with community-acquired pneumonia at the start and end of an exacerbation. We assessed neutrophils for spontaneous apoptosis, cell surface marker expression, degranulation, reactive oxygen species generation, phagocytosis, and killing of Pseudomonas aeruginosa (PAO1). In addition, blood neutrophil function was compared with airway neutrophil function in bronchiectasis.

MEASUREMENTS AND MAIN RESULTS

In stable bronchiectasis, compared with healthy volunteers, blood neutrophils had significantly prolonged viability, delayed apoptosis, increased CD62L shedding, upregulated CD11b expression, increased myeloperoxidase release, and impaired neutrophil phagocytosis and killing of PAO1. Bronchiectatic airway neutrophils had significantly lower bacterial phagocytosis and killing than their matched autologous blood neutrophils. Both blood and airway neutrophil phagocytosis and killing were impaired at the start of an exacerbation and improved following antibiotic treatment. In pneumonia, there was a significant improvement in phagocytosis and killing after treatment with antibiotics. During infections, there was no difference in phagocytosis, but there was significantly increased bacterial killing at the start and end of infection in pneumonia compared with bronchiectasis exacerbations.

CONCLUSIONS

In bronchiectasis stable state, peripheral blood neutrophils are reprogrammed and have prolonged survival. This impairs their functional ability of bacterial phagocytosis and killing, thereby perpetuating the vicious circle in bronchiectasis.

ROCK Inhibition Drives Resolution of Acute Inflammation by Enhancing Neutrophil Apoptosis

Uncontrolled inflammation leads to tissue damage and it is central for the development of chronic inflammatory diseases and autoimmunity. An acute inflammatory response is finely regulated by the action of anti-inflammatory and pro-resolutive mediators, culminating in the resolution of inflammation and restoration of homeostasis. There are few studies investigating intracellular signaling pathways associated with the resolution of inflammation. Here, we investigate the role of Rho-associated kinase (ROCK), a serine/threonine kinase, in a model of self-resolving neutrophilic inflammatory. We show that ROCK activity, evaluated by P-MYPT-1 kinetics, was higher during the peak of lipopolysaccharide-induced neutrophil influx in the pleural cavity of mice. ROCK inhibition by treatment with Y-27632 decreased the accumulation of neutrophils in the pleural cavity and was associated with an increase in apoptotic events and efferocytosis, as evaluated by an in vivo assay. In a model of gout, treatment with Y-27632 reduced neutrophil accumulation, IL-1β levels and hypernociception in the joint. These were associated with reduced MYPT and IκBα phosphorylation levels and increased apoptosis. Finally, inhibition of ROCK activity also induced apoptosis in human neutrophils and destabilized cytoskeleton, extending the observed effects to human cells. Taken together, these data show that inhibition of the ROCK pathway might represent a potential therapeutic target for neutrophilic inflammatory diseases.

Inflammation Resolution and the Induction of Granulocyte Apoptosis by Cyclin-Dependent Kinase Inhibitor Drugs

Inflammation is a necessary dynamic tissue response to injury or infection and it's resolution is essential to return tissue homeostasis and function. Defective or dysregulated inflammation resolution contributes significantly to the pathogenesis of many, often common and challenging to treat human conditions. The transition of inflammation to resolution is an active process, involving the clearance of inflammatory cells (granulocytes), a change of mediators and their receptors, and prevention of further inflammatory cell infiltration. This review focuses on the use of cyclin dependent kinase inhibitor drugs to pharmacologically target this inflammatory resolution switch, specifically through inducing granulocyte apoptosis and phagocytic clearance of apoptotic cells (efferocytosis). The key processes and pathways required for granulocyte apoptosis, recruitment of phagocytes and mechanisms of engulfment are discussed along with the cumulating evidence for cyclin dependent kinase inhibitor drugs as pro-resolution therapeutics.

The significant impact of apigenin on different aspects of autoimmune disease

Autoimmune diseases are among the highest diseases to diagnose and treat. The current "gold standard" of care for these diseases is immunosuppressive drugs which interfere with overall immune responses; their long-term high-dose treatments would expose the patient to opportunistic, life-threatening and long-term malignant infections. Considering the side effects and toxicity of these drug and also the beneficial effects of herbal compounds among their consumers, the professional investigation on the exact mechanism of the plant's major element has grown much attention in the last years. Apigenin as an extracting compound of plants, such as parsley and celery, which has a variety of biological effects, such as anti-inflammatory, anti-cancer and antioxidant effects. This review is intended to summarize the various effects of Apigenin on several autoimmune diseases which have been worked on so far. The pluralization of the obtained results has revealed Apigenin's effects on pro-inflammatory cytokines such as IL-1β, chemokines such as ICAM-1, immune cells proliferation such as T cells, apoptosis, and various signaling pathways. According to these preclinical findings, we recommend that further robust unbiased studies should be done to use Apigenin as a supplementary or therapeutic element in autoimmune disease.

Inhibition of Myosin Light-Chain Kinase Enhances the Clearance of Lipopolysaccharide-Induced Lung Inflammation Possibly by Accelerating Neutrophil Apoptosis

Neutrophils are a population of inflammatory cells involved in acute lung injury (ALI), and lipopolysaccharide (LPS)-induced prolonged neutrophil survival and delayed neutrophil apoptosis hinder the alleviation of lung inflammation. Myosin light-chain kinase (MLCK) involved the RhoA/Rho kinase signaling pathway responsible for the cytoskeletal arrangement, and previous studies have revealed that inhibition of MLCK induces apoptosis in vitro and in vivo. In this study, glycogen-induced neutrophils isolated from rats or mice were incubated with ML-7, a MLCK-specific inhibitor, and LPS-induced ALI mice administrated with ML-7 were investigated, to demonstrate the roles of MLCK in neutrophil apoptosis as well as its possibility of contributing to the clearance of inflammation. We found that ML-7 dramatically promoted neutrophil apoptosis that possibly signal through the p38 to upregulate the expression of the apoptotic proteins caspase-9 and B-cell lymphoma 2 and to downregulate the expression of the antiapoptotic protein Bcl-2-associated X protein and myeloid cell leukemia-1. In mice, ML-7 accelerated the clearance of inflammation in LPS-induced ALI through attenuating neutrophil accumulation, histopathological changes, and pulmonary edema. ML-7 promoted elimination of inflammation possibly by accelerating neutrophil apoptosis and macrophage-mediated clearance. Moreover, ML-7 also reduced the LPS-induced production of proinflammatory cytokines interleukin-1β and tumor necrosis factor-α, and the activity of myeloperoxidase. Taken together, the present study uncovers a hitherto uncharacterized role of MLCK in neutrophil apoptosis that contributes to the alleviation of inflammation in response to LPS.

Palmitic acid, but not high-glucose, induced myocardial apoptosis is alleviated by N‑acetylcysteine due to attenuated mitochondrial-derived ROS accumulation-induced endoplasmic reticulum stress

Pharmacological inhibition of reactive oxygen species (ROS) is a potential strategy to prevent diabetes-induced cardiac dysfunction. This study was designed to investigate precise effects of antioxidant N‑acetylcysteine (NAC) in alleviating diabetic cardiomyopathy (DCM). Echocardiography and histologic studies were performed 12 weeks after streptozocin injection. Protein levels involved in endoplasmic reticulum stress (ERS) and apoptosis were analyzed by western blotting in diabetic hearts or high-glucose (HG, 30 mM)- and palmitic acid (PA, 300 μM)-cultured neonatal rat cardiomyocytes (NRCMs). ROS generation and structural alterations of mitochondria were also assessed. We report that NAC alleviated diabetes-induced cardiac abnormality, including restored ejection fraction (EF %), fraction shortening (FS %), peak E to peak A ratio (E/A) and reduced cardiac hypertrophy and fibrosis. These effects were concomitant with blocked ERS and apoptosis, as evidenced by inactivation of phosphorylated inositol-requiring enzyme-1α (IRE1α)/spliced X-box binding protein 1 (XBP1), phosphorylated protein kinase-like kinase (PERK)/phosphorylated eukaryotic initiation factor 2α (eIF2α) and glucose-regulated protein 78 (GRP78)/activating transcription factor 6 (ATF6α)/C/EBP homologous protein (CHOP) pathways, as well as suppressed Bcl-2-associated X protein (BAX)/B-cell lymphoma-2 (Bcl-2) and cleaved caspase 3 expressions. Mechanistically, PA mediated excessive mitochondrial ROS generation and oxidative stress, which were antagonized by NAC and Mito-TEMPO, a mitochondrial ROS inhibitor. No effects were noted by addition of apocynin, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, and NADPH oxidase 4 (NOX 4) and NOX 2 expressions were not altered, indicating that PA-induced ROS generation is independent of NADPH oxidases. Most intriguingly, HG failed to promote ROS production despite its ability to promote ERS and apoptosis in NRCMs. Collectively, these findings indicate that NAC primarily abrogates PA-mediated mitochondrial ROS through ERS and therefore alleviates myocardial apoptosis but has little effect on HG-induced cardiac injury. This uncovers a potential role for NAC in formulating novel cardioprotective strategies in DCM patients.

Wogonin attenuates nasal polyp formation by inducing eosinophil apoptosis through HIF-1α and survivin suppression

Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) is an inflammatory sinonasal disorder characterized by eosinophilic inflammation and T-helper 2 skewing. Eosinophil accumulation in sinonasal mucosa comprises a major feature of CRSwNP. The study aimed to investigate the effect of the flavone wogonin in nasal polyposis by assessing its ability to induce eosinophil apoptosis in vitro and attenuate eosinophilic CRSwNP in mice. Double immunofluorescence, immunohistochemistry, flow cytometry, and immunoblotting were performed to evaluate hypoxia-inducible factor (HIF)-1α, survivin, and apoptotic markers in the human eosinophilic EoL-1 cell line or sinonasal tissues from patients with CRS with or without NPs. In sinonasal specimens from patients with CRS, HIF-1α and survivin were up-regulated in eosinophils from patients with NPs compared with levels in patients without NPs. Under hypoxia, HIF-1α and survivin expression was up-regulated in EoL-1 cells. Wogonin down-regulated both HIF-1α and survivin in EoL-1 cells. In addition, overexpression of survivin protected EoL-1 cells against apoptosis in response to wogonin. Moreover, wogonin attenuated nasal polyp formation in a murine model. Our findings suggest that wogonin could induce caspase-3 activation by suppressing HIF-1α and survivin expression in EoL-1 cells. Further studies regarding novel therapeutic options for CRSwNP targeting eosinophil apoptosis are needed.

Complementary effects of cereal and pulse polyphenols and dietary fiber on chronic inflammation and gut health

Cereal grains and grain pulses are primary staples often consumed together, and contribute a major portion of daily human calorie and protein intake globally. Protective effects of consuming whole grain cereals and grain pulses against various inflammation-related chronic diseases are well documented. However, potential benefits of combined intake of whole cereals and pulses beyond their complementary amino acid nutrition is rarely considered in literature. There is ample evidence that key bioactive components of whole grain cereals and pulses are structurally different and thus may be optimized to provide synergistic/complementary health benefits. Among the most important whole grain bioactive components are polyphenols and dietary fiber, not only because of their demonstrated biological function, but also their major impact on consumer choice of whole grain/pulse products. This review highlights the distinct structural differences between key cereal grain and pulse polyphenols and non-starch polysaccharides (dietary fiber), and the evidence on specific synergistic/complementary benefits of combining the bioactive components from the two commodities. Interactive effects of the polyphenols and fiber on gut microbiota and associated benefits to colon health, and against systemic inflammation, are discussed. Processing technologies that can be used to further enhance the interactive benefits of combined cereal-pulse bioactive compounds are highlighted.

The co-treatment of metformin with flavone synergistically induces apoptosis through inhibition of PI3K/AKT pathway in breast cancer cells

Metformin, a widely used antidiabetic drug, exhibits anticancer effects which are mediated by the phosphatidylinositol 3-kinase (PI3K)/serine/threonine kinase (AKT) signaling pathway. However, its use in anticancer therapy combined with other natural products remains unclear. Flavone as the core structure of flavonoids has been demonstrated to induce cell apoptosis without causing serious side effect. Murine double minute X (MDMX) inhibits tumor suppressor gene p53 whose function is associated with the PI3K/AKT pathway. The results presented herein revealed that the combination of metformin and flavone significantly inhibited cell viability, and increased apoptosis of human breast cancer cells compared with metformin or flavone alone. The combination decreased the protein expression of MDMX, activated p53 through the PI3K/AKT signaling pathway, regulated p53 downstream target genes Bcl-2 apoptosis regulator, BCL2 associated X apoptosis regulator and cleaved caspase3, subsequently inducing apoptosis in MDA-MB-231 and MCF-7 breast cancer cells. These results indicated that dietary flavone may potentiate breast cancer cell apoptosis induced by metformin, and PI3K/AKT is involved in regulating MDMX/p53 signaling. This data suggests that dietary supplementary of flavone is a promising strategy for metformin mediated anticancer effects.

Mer-mediated eosinophil efferocytosis regulates resolution of allergic airway inflammation

Background

Eosinophils play a central role in propagation of allergic diseases, including asthma. Both recruitment and retention of eosinophils regulate pulmonary eosinophilia, but the question of whether alterations in apoptotic cell clearance by phagocytes contributes directly to resolution of allergic airway inflammation remains unexplored.

Objectives

In this study we investigated the role of the receptor tyrosine kinase Mer in mediating apoptotic eosinophil clearance and allergic airway inflammation resolution in vivo to establish whether apoptotic cell clearance directly affects the resolution of allergic airway inflammation.

Methods

Alveolar and bone marrow macrophages were used to study Mer-mediated phagocytosis of apoptotic eosinophils. Allergic airway inflammation resolution was modeled in mice by using ovalbumin. Fluorescently labeled apoptotic cells were administered intratracheally or eosinophil apoptosis was driven by administration of dexamethasone to determine apoptotic cell clearance in vivo.

Results

Inhibition or absence of Mer impaired phagocytosis of apoptotic human and mouse eosinophils by macrophages. Mer-deficient mice showed delayed resolution of ovalbumin-induced allergic airway inflammation, together with increased airway responsiveness to aerosolized methacholine, increased bronchoalveolar lavage fluid protein levels, altered cytokine production, and an excess of uncleared dying eosinophils after dexamethasone treatment. Alveolar macrophage phagocytosis was significantly Mer dependent, with the absence of Mer attenuating apoptotic cell clearance in vivo to enhance inflammation in response to apoptotic cells.

Conclusions

We demonstrate that Mer-mediated apoptotic cell clearance by phagocytes contributes to resolution of allergic airway inflammation, suggesting that augmenting apoptotic cell clearance is a potential therapeutic strategy for treating allergic airway inflammation.

Adoption of in vitro systems and zebrafish embryos as alternative models for reducing rodent use in assessments of immunological and oxidative stress responses to nanomaterials

Assessing the safety of engineered nanomaterials (NMs) is paramount to the responsible and sustainable development of nanotechnology, which provides huge societal benefits. Currently, there is no evidence that engineered NMs cause detrimental health effects in humans. However, investigation of NM toxicity using in vivo, in vitro, in chemico, and in silico models has demonstrated that some NMs stimulate oxidative stress and inflammation, which may lead to adverse health effects. Accordingly, investigation of these responses currently dominates NM safety assessments. There is a need to reduce reliance on rodent testing in nanotoxicology for ethical, financial and legislative reasons, and due to evidence that rodent models do not always predict the human response. We advocate that in vitro models and zebrafish embryos should have greater prominence in screening for NM safety, to better align nanotoxicology with the 3Rs principles. Zebrafish are accepted for use by regulatory agencies in chemical safety assessments (e.g. developmental biology) and there is growing acceptance of their use in biomedical research, providing strong foundations for their use in nanotoxicology. We suggest that investigation of the response of phagocytic cells (e.g. neutrophils, macrophages) in vitro should also form a key part of NM safety assessments, due to their prominent role in the first line of defense. The development of a tiered testing strategy for NM hazard assessment that promotes the more widespread adoption of non-rodent, alternative models and focuses on investigation of inflammation and oxidative stress could make nanotoxicology testing more ethical, relevant, and cost and time efficient.

Non-canonical PI3K-Cdc42-Pak-Mek-Erk Signaling Promotes Immune-Complex-Induced Apoptosis in Human Neutrophils

Neutrophils are peripheral blood leukocytes that represent the first line of immune cell defense against bacterial and fungal infections but are also crucial players in the generation of the inflammatory response. Many neutrophil cell surface receptors regulate important cellular processes via activation of agonist-activated PI3Ks. We show here that activation of human neutrophils with insoluble immune complexes drives a previously uncharacterized, PI3K-dependent, non-canonical, pro-apoptotic signaling pathway, FcγR-PI3Kβ/δ-Cdc42-Pak-Mek-Erk. This is a rare demonstration of Ras/Raf-independent activation of Erk and of PI3K-mediated activation of Cdc42. In addition, comparative analysis of immune-complex- and fMLF-induced signaling uncovers key differences in pathways used by human and murine neutrophils. The non-canonical pathway we identify in this study may be important for the resolution of inflammation in chronic inflammatory diseases that rely on immune-complex-driven neutrophil activation.

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Immune-complex-activated human neutrophils use PI3Kβ/δ-Cdc42-Pak-Mek-Erk signaling

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Immune-complex-induced non-canonical neutrophil signaling is pro-apoptotic

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Other immune-complex-induced neutrophil functions depend on alternative PI3K effectors

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Immune-complex-induced PI3K signaling is not conserved between humans and mice

Apigenin inhibits colonic inflammation and tumorigenesis by suppressing STAT3-NF-κB signaling

Apigenin is a naturally occurring compound with anti-inflammatory, antioxidant, and anticancer properties. Here, we investigated the effects of apigeninin inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). Apigenin effectively inhibited ulcerative colitis, a type of IBD, and CAC. Apigenin decreased myeloperoxidase (MPO), inflammatory cytokine and COX-2 levels, and it attenuated inflammatory cell infiltration in treated colon tissues as compared to untreated model colon tissues. Apigenin also reduced NF-κB and STAT3 activity in vitro and in vivo, thereby inhibiting inflammation and inflammation-induced carcinogenesis. Thus apigenin appears to inhibit inflammation and inflammation-induced carcinogenesisin IBD and CAC by suppressing STAT3-NF-κB signaling.

Delayed neutrophil apoptosis enhances NET formation in cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) lung disease is defined by large numbers of neutrophils and associated damaging products in the airway. Delayed neutrophil apoptosis is described in CF although it is unclear whether this is a primary neutrophil defect or a response to chronic inflammation. Increased levels of neutrophil extracellular traps (NETs) have been measured in CF and we aimed to investigate the causal relationship between these phenomena and their potential to serve as a driver of inflammation. We hypothesised that the delay in apoptosis in CF is a primary defect and preferentially allows CF neutrophils to form NETs, contributing to inflammation.

METHODS

Blood neutrophils were isolated from patients with CF, CF pigs and appropriate controls. Neutrophils were also obtained from patients with CF before and after commencing ivacaftor. Apoptosis was assessed by morphology and flow cytometry. NET formation was determined by fluorescent microscopy and DNA release assays. NET interaction with macrophages was examined by measuring cytokine generation with ELISA and qRT-PCR.

RESULTS

CF neutrophils live longer due to decreased apoptosis. This was observed in both cystic fibrosis transmembrane conductance regulator (CFTR) null piglets and patients with CF, and furthermore was reversed by ivacaftor (CFTR potentiator) in patients with gating (G551D) mutations. CF neutrophils formed more NETs and this was reversed by cyclin-dependent kinase inhibitor exposure. NETs provided a proinflammatory stimulus to macrophages, which was enhanced in CF.

CONCLUSIONS

CF neutrophils have a prosurvival phenotype that is associated with an absence of CFTR function and allows increased NET production, which can in turn induce inflammation. Augmenting neutrophil apoptosis in CF may allow more appropriate neutrophil disposal, decreasing NET formation and thus inflammation.

The resolution of acute inflammation induced by cyclic AMP is dependent on annexin A1

Annexin A1 (AnxA1) is a glucocorticoid-regulated protein known for its anti-inflammatory and pro-resolving effects. We have shown previously that the cAMP-enhancing compounds rolipram (ROL; a PDE4 inhibitor) and Bt₂cAMP (a cAMP mimetic) drive caspase-dependent resolution of neutrophilic inflammation. In this follow-up study, we investigated whether AnxA1 could be involved in the pro-resolving properties of these compounds using a model of LPS-induced inflammation in BALB/c mice. The treatment with ROL or Bt₂cAMP at the peak of inflammation shortened resolution intervals, improved resolution indices, and increased AnxA1 expression. In vitro studies showed that ROL and Bt₂cAMP induced AnxA1 expression and phosphorylation, and this effect was prevented by PKA inhibitors, suggesting the involvement of PKA in ROL-induced AnxA1 expression. Akin to these in vitro findings, H89 prevented ROL- and Bt₂cAMP-induced resolution of inflammation, and it was associated with decreased levels of intact AnxA1. Moreover, two different strategies to block the AnxA1 pathway (by using N-t-Boc-Met-Leu-Phe, a nonselective AnxA1 receptor antagonist, or by using an anti-AnxA1 neutralizing antiserum) prevented ROL- and Bt₂cAMP-induced resolution and neutrophil apoptosis. Likewise, the ability of ROL or Bt₂cAMP to induce neutrophil apoptosis was impaired in AnxA-knock-out mice. Finally, in in vitro settings, ROL and Bt₂cAMP overrode the survival-inducing effect of LPS in human neutrophils in an AnxA1-dependent manner. Our results show that AnxA1 is at least one of the endogenous determinants mediating the pro-resolving properties of cAMP-elevating agents and cAMP-mimetic drugs.

Application of luteolin nanomicelles anti-glioma effect with improvement in vitro and in vivo

Glioblastoma multiforme (GBM) is one of the most common and malignant tumor. Luteolin, a polyphenolic compound, has been proposed to have anti-tumor activity against various cancers. However, the greatest obstacle in the administration of luteolin is its hydrophobicity as well as the low oral bioavailability. In this study, we formulated luteolin-loaded MPEG-PCL (Luteolin/MPEG-PCL) micelles aiming to improve its solubility in aqueous solution and investigate the anti-tumor effect on glioma in vitro and in vivo. The spherical Luteolin/MPEG-PCL micelles were completely dispersible in normal saline and could release luteolin in a sustained manner in vitro. We demonstrated that Luteolin/MPEG-PCL micelles had stronger cytotoxicity and induced a higher percentage of apoptosis in C6 and U87 cells than free luteolin in vitro. The immunohistochemical study revealed that Luteolin/MPEG-PCL micelles induced more glioma cell apoptosis than free luteolin and inhibited neovascularization in tumor tissues. The Pro-caspase9 and Bcl-2 down-regulation and cleaved-caspase9 and Bax up-regulation suggested that luteolin induced apoptosis via the mitochondrial pathway in vitro. What is more, we found the drug could cumulated much more in the nano-drug group than free drug group through imaging in vivo. In conclusion, the Luteolin/MPEG-PCL micelles have the potential clinical application in glioma chemotherapy.

The many ways tissue phagocytes respond to dying cells

Apoptosis is an important component of normal tissue physiology, and the prompt removal of apoptotic cells is equally essential to avoid the undesirable consequences of their accumulation and disintegration. Professional phagocytes are highly specialized for engulfing apoptotic cells. The recent ability to track cells that have undergone apoptosis in situ has revealed a division of labor among the tissue resident phagocytes that sample them. Macrophages are uniquely programmed to process internalized apoptotic cell-derived fatty acids, cholesterol and nucleotides, as a reflection of their dominant role in clearing the bulk of apoptotic cells. Dendritic cells carry apoptotic cells to lymph nodes where they signal the emergence and expansion of highly suppressive regulatory CD4 T cells. A broad suppression of inflammation is executed through distinct phagocyte-specific mechanisms. A clever induction of negative regulatory nodes is notable in dendritic cells serving to simultaneously shut down multiple pathways of inflammation. Several of the genes and pathways modulated in phagocytes in response to apoptotic cells have been linked to chronic inflammatory and autoimmune diseases such as atherosclerosis, inflammatory bowel disease and systemic lupus erythematosus. Our collective understanding of old and new phagocyte functions after apoptotic cell phagocytosis demonstrates the enormity of ways to mediate immune suppression and enforce tissue homeostasis.

Genetic and pharmacological inhibition of CDK9 drives neutrophil apoptosis to resolve inflammation in zebrafish in vivo

Neutrophilic inflammation is tightly regulated and subsequently resolves to limit tissue damage and promote repair. When the timely resolution of inflammation is dysregulated, tissue damage and disease results. One key control mechanism is neutrophil apoptosis, followed by apoptotic cell clearance by phagocytes such as macrophages. Cyclin-dependent kinase (CDK) inhibitor drugs induce neutrophil apoptosis in vitro and promote resolution of inflammation in rodent models. Here we present the first in vivo evidence, using pharmacological and genetic approaches, that CDK9 is involved in the resolution of neutrophil-dependent inflammation. Using live cell imaging in zebrafish with labelled neutrophils and macrophages, we show that pharmacological inhibition, morpholino-mediated knockdown and CRISPR/cas9-mediated knockout of CDK9 enhances inflammation resolution by reducing neutrophil numbers via induction of apoptosis after tailfin injury. Importantly, knockdown of the negative regulator La-related protein 7 (LaRP7) increased neutrophilic inflammation. Our data show that CDK9 is a possible target for controlling resolution of inflammation.

Key mechanisms governing resolution of lung inflammation

Innate immunity normally provides excellent defence against invading microorganisms. Acute inflammation is a form of innate immune defence and represents one of the primary responses to injury, infection and irritation, largely mediated by granulocyte effector cells such as neutrophils and eosinophils. Failure to remove an inflammatory stimulus (often resulting in failed resolution of inflammation) can lead to chronic inflammation resulting in tissue injury caused by high numbers of infiltrating activated granulocytes. Successful resolution of inflammation is dependent upon the removal of these cells. Under normal physiological conditions, apoptosis (programmed cell death) precedes phagocytic recognition and clearance of these cells by, for example, macrophages, dendritic and epithelial cells (a process known as efferocytosis). Inflammation contributes to immune defence within the respiratory mucosa (responsible for gas exchange) because lung epithelia are continuously exposed to a multiplicity of airborne pathogens, allergens and foreign particles. Failure to resolve inflammation within the respiratory mucosa is a major contributor of numerous lung diseases. This review will summarise the major mechanisms regulating lung inflammation, including key cellular interplays such as apoptotic cell clearance by alveolar macrophages and macrophage/neutrophil/epithelial cell interactions. The different acute and chronic inflammatory disease states caused by dysregulated/impaired resolution of lung inflammation will be discussed. Furthermore, the resolution of lung inflammation during neutrophil/eosinophil-dominant lung injury or enhanced resolution driven via pharmacological manipulation will also be considered.

Identification of benzopyrone as a common structural feature in compounds with anti-inflammatory activity in a zebrafish phenotypic screen

Neutrophils are essential for host defence and are recruited to sites of inflammation in response to tissue injury or infection. For inflammation to resolve, these cells must be cleared efficiently and in a controlled manner, either by apoptosis or reverse migration. If the inflammatory response is not well-regulated, persistent neutrophils can cause damage to host tissues and contribute to the pathogenesis of chronic inflammatory diseases, which respond poorly to current treatments. It is therefore important to develop drug discovery strategies that can identify new therapeutics specifically targeting neutrophils, either by promoting their clearance or by preventing their recruitment. Our recent in vivo chemical genetic screen for accelerators of inflammation resolution identified a subset of compounds sharing a common chemical signature, the bicyclic benzopyrone rings. Here, we further investigate the mechanisms of action of the most active of this chemical series, isopimpinellin, in our zebrafish model of neutrophilic inflammation. We found that this compound targets both the recruitment and resolution phases of the inflammatory response. Neutrophil migration towards a site of injury is reduced by isopimpinellin and this occurs as a result of PI3K inhibition. We also show that isopimpinellin induces neutrophil apoptosis to drive inflammation resolution in vivo using a new zebrafish reporter line detecting in vivo neutrophil caspase-3 activity and allowing quantification of flux through the apoptotic pathway in real time. Finally, our studies reveal that clinically available ‘cromones’ are structurally related to isopimpinellin and have previously undescribed pro-resolution activity in vivo. These findings could have implications for the therapeutic use of benzopyrones in inflammatory disease.

Summary: Zebrafish inflammation screen identifies a new series of structurally related compounds with combined anti-inflammatory and pro-resolution activity, and reveals a previously unknown mechanism of action of clinical cromones.

Dietary Apigenin Exerts Immune-Regulatory Activity in Vivo by Reducing NF-κB Activity, Halting Leukocyte Infiltration and Restoring Normal Metabolic Function

The increasing prevalence of inflammatory diseases and the adverse effects associated with the long-term use of current anti-inflammatory therapies prompt the identification of alternative approaches to reestablish immune balance. Apigenin, an abundant dietary flavonoid, is emerging as a potential regulator of inflammation. Here, we show that apigenin has immune-regulatory activity in vivo. Apigenin conferred survival to mice treated with a lethal dose of Lipopolysaccharide (LPS) restoring normal cardiac function and heart mitochondrial Complex I activity. Despite the adverse effects associated with high levels of splenocyte apoptosis in septic models, apigenin had no effect on reducing cell death. However, we found that apigenin decreased LPS-induced apoptosis in lungs, infiltration of inflammatory cells and chemotactic factors’ accumulation, re-establishing normal lung architecture. Using NF-κB luciferase transgenic mice, we found that apigenin effectively modulated NF-κB activity in the lungs, suggesting the ability of dietary compounds to exert immune-regulatory activity in an organ-specific manner. Collectively, these findings provide novel insights into the underlying immune-regulatory mechanisms of dietary nutraceuticals in vivo.

LYG-202 exerts antitumor effect on PI3K/Akt signaling pathway in human breast cancer cells

In this study, we aimed to investigate the antitumor effect of LYG-202, a newly synthesized piperazine-substituted derivative of flavonoid on human breast cancer cells and illustrate the potential mechanisms. LYG-202 induced apoptosis in MCF-7, MDA-MB-231 and MDA-MB-435 cells. LYG-202 triggered the activation of mitochondrial apoptotic pathway through multiple steps: increasing Bax/Bcl-2 ratio, decreasing mitochondrial membrane potential (ΔΨ(m)), activating caspase-9 and caspase-3, inducing cleavage of poly(ADP-ribose) polymerase, cytochrome c release and apoptosis-inducing factor translocation. Furthermore, LYG-202 inhibited cell cycle progression at the G1/S transition via targeting Cyclin D, CDK4 and p21(Waf1/Cip1). Additionally, LYG-202 increased the generation of intracellular ROS. N-Acetyl cysteine, an antioxidant, reversed LYG-202-induced apoptosis suggesting that LYG-202 induces apoptosis by accelerating ROS generation. Further, we found that LYG-202 deactivated the PI3K/Akt pathway, activated Bad phosphorylation, increased Cyclin D and Bcl-xL expression, and inhibited NF-κB nuclear translocation. Activation of PI3K/Akt pathway by IGF-1 attenuated LYG-202-induced apoptosis and cell cycle arrest. Our in vivo study showed that LYG-202 exhibited a potential antitumor effect in nude mice inoculated with MCF-7 tumor through similar mechanisms identified in cultured cells. In summary, our results demonstrated that LYG-202 induced apoptosis and cell cycle arrest via targeting PI3K/Akt pathway, indicating that LYG-202 is a potential anticancer agent for breast cancer.

Proresolving Actions of Synthetic and Natural Protease Inhibitors Are Mediated by Annexin A1

Annexin A1 (AnxA1) is a glucocorticoid-regulated protein endowed with anti-inflammatory and proresolving properties. Intact AnxA1 is a 37-kDa protein that may be cleaved in vivo at the N-terminal region by neutrophil proteases including elastase and proteinase-3, generating the 33-kDa isoform that is largely inactive. In this study, we investigated the dynamics of AnxA1 expression and the effects of synthetic (sivelestat [SIV]; Eglin) and natural (secretory leukocyte protease inhibitor [SLPI]; Elafin) protease inhibitors on the resolution of LPS-induced inflammation. During the settings of LPS inflammation AnxA1 cleavage associated closely with the peak of neutrophil and elastase expression and activity. SLPI expression increased during resolving phase of the pleurisy. Therapeutic treatment of LPS-challenge mice with recombinant human SLPI or Elafin accelerated resolution, an effect associated with increased numbers of apoptotic neutrophils in the pleural exudates, inhibition of elastase, and modulation of the survival-controlling proteins NF-κB and Mcl-1. Similar effects were observed with SIV, which dose-dependently inhibited neutrophil elastase and shortened resolution intervals. Mechanistically, SIV-induced resolution was caspase-dependent, associated to increased levels of intact AnxA1 and decreased expression of NF-κB and Mcl-1. The proresolving effect of antiproteases was also observed in a model of monosodium urate crystals-induced inflammation. SIV skewed macrophages toward resolving phenotypes and enhanced efferocytosis of apoptotic neutrophils. A neutralizing antiserum against AnxA1 and a nonselective antagonist of AnxA1 receptor abolished the accelerated resolution promoted by SIV. Collectively, these results show that elastase inhibition not only inhibits inflammation but actually promotes resolution, and this response is mediated by protection of endogenous intact AnxA1 with ensuing augmentation of neutrophil apoptosis.

Models for the Study of the Cross Talk Between Inflammation and Cell Cycle

Cyclin-dependent kinases (CDKs) have been traditionally associated with the cell cycle. However, it is now known that CDK7 and CDK9 regulate transcriptional activity via phosphorylation of RNA polymerase II and subsequent synthesis of, for example, inflammatory mediators and factors that influence the apoptotic process; including apoptosis of granulocytes such as neutrophils and eosinophils. Successful resolution of inflammation and restoration of normal tissue homeostasis requires apoptosis of these inflammatory cells and subsequent clearance of apoptotic bodies by phagocytes such as macrophages. It is believed that CDK7 and CDK9 influence resolution of inflammation since they are involved in the transcription of anti-apoptotic proteins such as Mcl-1 which is especially important in granulocyte survival.This chapter describes various in vitro and in vivo models used to investigate CDKs and their inhibitors in granulocytes and particularly the role of CDKs in the apoptosis pathway. This can be performed in vitro by isolation and use of primary granulocytes and in vivo using animal models of inflammatory disease in rodents and zebrafish. Some of the methods described here to assess the role of CDKs in inflammation and apoptosis include flow cytometry and western blotting, together with imaging and quantification of apoptosis in fixed tissue, as well as in vivo models of inflammation.

Wogonin induces eosinophil apoptosis and attenuates allergic airway inflammation

RATIONALE

Eosinophils are key effector cells in allergic diseases, including allergic rhinitis, eczema, and asthma. Their tissue presence is regulated by both recruitment and increased longevity at inflamed sites.

OBJECTIVES

To investigate the ability of the flavone wogonin to induce eosinophil apoptosis in vitro and attenuate eosinophil-dominant allergic inflammation in vivo in mice.

METHODS

Human and mouse eosinophil apoptosis in response to wogonin was investigated by cellular morphology, flow cytometry, mitochondrial membrane permeability, and pharmacological caspase inhibition. Allergic lung inflammation was modeled in mice sensitized and challenged with ovalbumin. Bronchoalveolar lavage (BAL) and lung tissue were examined for inflammation, mucus production, and inflammatory mediator production. Airway hyperresponsiveness to aerosolized methacholine was measured.

MEASUREMENTS AND MAIN RESULTS

Wogonin induced time- and concentration-dependent human and mouse eosinophil apoptosis in vitro. Wogonin-induced eosinophil apoptosis occurred with activation of caspase-3 and was inhibited by pharmacological caspase inhibition. Wogonin administration attenuated allergic airway inflammation in vivo with reductions in BAL and interstitial eosinophil numbers, increased eosinophil apoptosis, reduced airway mucus production, and attenuated airway hyperresponsiveness. This wogonin-induced reduction in allergic airway inflammation was prevented by concurrent caspase inhibition in vivo.

CONCLUSIONS

Wogonin induces eosinophil apoptosis and attenuates allergic airway inflammation, suggesting that it has therapeutic potential for the treatment of allergic inflammation in humans.

Mechanisms of apoptosis inhibition in Chlamydia pneumoniae-infected neutrophils

The obligatory intracellular bacterium Chlamydia pneumoniae (C. pneumoniae) can survive and multiply in neutrophil granulocytes. Since neutrophils are short living cells, inhibition of neutrophil apoptosis appears to play a major role in the productive infection of neutrophils by C. pneumoniae. In the present study, we have investigated which survival pathways and which events of the apoptotic process are modulated in C. pneumoniae-infected neutrophils. All infection experiments were carried out using primary human neutrophils in vitro. We show that infection with C. pneumoniae activates PI3K/Akt as well as the ERK1/2 and p38 MAP kinases and present evidence that activation of the PI3K/Akt and ERK1/2 pathways are essential to initiate the apoptosis delay in C. pneumoniae-infected neutrophils. Both the PI3K/Akt and ERK1/2 pathways are involved in the maintained expression of the anti-apoptotic protein Mcl-1. In addition, we also showed that the PI3K/Akt pathway leads to the activation of NF-κB-dependent release of IL-8 by infected neutrophils. Infection with C. pneumoniae activates the PI3K/Akt and ERK1/2 MAPK survival pathways in neutrophils, induces the NF-κB dependent release of IL-8 and leads to the maintenance of Mcl-1 expression in neutrophils.

Implementation of validated pharmacodynamic assays in multiple laboratories: challenges, successes, and limitations

There is a "life cycle" of pharmacodynamic (PD) biomarker assays that guides the development and clinical implementation in our laboratories. The well-recognized elements of analytical assay validation and demonstration of fitness-for-purpose of the biomarker, specimen collection, handling, and assay methods are only a part of the required activities. Assay transfer across laboratories and testing on actual human clinical specimens are vital for understanding assay performance and robustness. In our experience, this patient specimen-centered approach has required assay method modifications, some unexpected, but which were critical to successful implementation in clinical trials. In addition, dispersing assays throughout the National Cancer Institute's clinical trials network has required the development of calibrator and control materials as well as formal training courses for smooth implementation. One measure of success of this approach has been that a number of the assays developed at NCI's Frederick National Laboratory have ultimately reached the stage of commercialization, enabling wide accessibility of the PD biomarker assays by the research community. See all articles in this ccr focus section, "Progress in pharmacodynamic endpoints."

Wogonin prevents lipopolysaccharide-induced acute lung injury and inflammation in mice via peroxisome proliferator-activated receptor gamma-mediated attenuation of the nuclear factor-kappaB pathway

Acute lung injury (ALI) from a variety of clinical disorders, characterized by diffuse inflammation, is a cause of acute respiratory failure that develops in patients of all ages. Previous studies reported that wogonin, a flavonoid-like chemical compound which was found in Scutellaria baicalensis, has anti-inflammatory effects in several inflammation models, but not in ALI. Here, the in vivo protective effect of wogonin in the amelioration of lipopolysaccharide (LPS) -induced lung injury and inflammation was assessed. In addition, the in vitro effects and mechanisms of wogonin were studied in the mouse macrophage cell lines Ana-1 and RAW264.7. In vivo results indicated that wogonin attenuated LPS-induced histological alterations. Peripheral blood leucocytes decreased in the LPS-induced group, which was ameliorated by wogonin. In addition, wogonin inhibited the production of several inflammatory cytokines, including tumour necrosis factor-α, interleukin-1β (IL-1β) and IL-6, in the bronchoalveolar lavage fluid and lung tissues after LPS challenge, while the peroxisome proliferator-activated receptor γ (PPARγ) inhibitor GW9662 reversed these effects. In vitro results indicated that wogonin significantly decreased the secretion of IL-6, IL-1β and tumour necrosis factor-α in Ana-1 and RAW264.7 cells, which was suppressed by transfection of PPARγ small interfering RNA and GW9662 treatment. Moreover, wogonin activated PPARγ, induced PPARγ-mediated attenuation of the nuclear translocation and the DNA-binding activity of nuclear factor-κB in vivo and in vitro. In conclusion, all of these results showed that wogonin may serve as a promising agent for the attenuation of ALI-associated inflammation and pathology by regulating the PPARγ-involved nuclear factor-κB pathway.

Eosinophils in the lung - modulating apoptosis and efferocytosis in airway inflammation

Due to the key role of the lung in efficient transfer of oxygen in exchange for carbon dioxide, a controlled inflammatory response is essential for restoration of tissue homeostasis following airway exposure to bacterial pathogens or environmental toxins. Unregulated or prolonged inflammatory responses in the lungs can lead to tissue damage, disrupting normal tissue architecture, and consequently compromising efficient gaseous exchange. Failure to resolve inflammation underlies the development and/or progression of a number of inflammatory lung diseases including asthma. Eosinophils, granulocytic cells of the innate immune system, are primarily involved in defense against parasitic infections. However, the propagation of the allergic inflammatory response in chronic asthma is thought to involve excessive recruitment and impaired apoptosis of eosinophils together with defective phagocytic clearance of apoptotic cells (efferocytosis). In terms of therapeutic approaches for the treatment of asthma, the widespread use of glucocorticoids is associated with a number of adverse health consequences after long-term use, while some patients suffer from steroid-resistant disease. A new approach for therapeutic intervention would be to promote the resolution of inflammation via modulation of eosinophil apoptosis and the phagocytic clearance of apoptotic cells. This review focuses on the mechanisms underpinning eosinophil-mediated lung damage, currently available treatments and therapeutic targets that might in future be harnessed to facilitate inflammation resolution by the manipulation of cell survival and clearance pathways.

Downregulation of Mcl-1 has anti-inflammatory pro-resolution effects and enhances bacterial clearance from the lung

Phagocytes not only coordinate acute inflammation and host defense at mucosal sites, but also contribute to tissue damage. Respiratory infection causes a globally significant disease burden and frequently progresses to acute respiratory distress syndrome, a devastating inflammatory condition characterized by neutrophil recruitment and accumulation of protein-rich edema fluid causing impaired lung function. We hypothesized that targeting the intracellular protein myeloid cell leukemia 1 (Mcl-1) by a cyclin-dependent kinase inhibitor (AT7519) or a flavone (wogonin) would accelerate neutrophil apoptosis and resolution of established inflammation, but without detriment to bacterial clearance. Mcl-1 loss induced human neutrophil apoptosis, but did not induce macrophage apoptosis nor impair phagocytosis of apoptotic neutrophils. Neutrophil-dominant inflammation was modelled in mice by either endotoxin or bacteria (Escherichia coli). Downregulating inflammatory cell Mcl-1 had anti-inflammatory, pro-resolution effects, shortening the resolution interval (Ri) from 19 to 7 h and improved organ dysfunction with enhanced alveolar-capillary barrier integrity. Conversely, attenuating drug-induced Mcl-1 downregulation inhibited neutrophil apoptosis and delayed resolution of endotoxin-mediated lung inflammation. Importantly, manipulating lung inflammatory cell Mcl-1 also accelerated resolution of bacterial infection (Ri; 50 to 16 h) concurrent with enhanced bacterial clearance. Therefore, manipulating inflammatory cell Mcl-1 accelerates inflammation resolution without detriment to host defense against bacteria, and represents a target for treating infection-associated inflammation.

Nuclear Receptors and Clearance of Apoptotic Cells: Stimulating the Macrophage's Appetite

Clearance of apoptotic cells by macrophages occurs as a coordinated process to ensure tissue homeostasis. Macrophages play a dual role in this process; first, a rapid and efficient phagocytosis of the dying cells is needed to eliminate uncleared corpses that can promote inflammation. Second, after engulfment, macrophages exhibit an anti-inflammatory phenotype, to avoid unwanted immune reactions against cell components. Several nuclear receptors, including liver X receptor and proliferator-activated receptor, have been linked to these two important features of macrophages during apoptotic cell clearance. This review outlines the emerging implications of nuclear receptors in the response of macrophages to cell clearance. These include activation of genes implicated in metabolism, to process the additional cellular content provided by the engulfed cells, as well as inflammatory genes, to maintain apoptotic cell clearance as an “immunologically silent” process. Remarkably, genes encoding receptors for the so-called “eat-me” signals are also regulated by activated nuclear receptors after phagocytosis of apoptotic cells, thus enhancing the efficiency of macrophages to clear dead cells.