Targeting neutrophil apoptosis for enhancing the resolution of inflammation

Drug repurposing of cyclin-dependent kinase inhibitors for neutrophilic acute respiratory distress syndrome and psoriasis

BACKGROUND

Neutrophilic inflammation, characterized by dysregulated neutrophil activation, triggers a variety of inflammatory responses such as chemotactic infiltration, oxidative bursts, degranulation, neutrophil extracellular traps (NETs) formation, and delayed turnover. This type of inflammation is pivotal in the pathogenesis of acute respiratory distress syndrome (ARDS) and psoriasis. Despite current treatments, managing neutrophil-associated inflammatory symptoms remains a significant challenge.

AIM OF REVIEW

This review emphasizes the role of cyclin-dependent kinases (CDKs) in neutrophil activation and inflammation. It aims to highlight the therapeutic potential of repurposing CDK inhibitors to manage neutrophilic inflammation, particularly in ARDS and psoriasis. Additionally, it discusses the necessary precautions for the clinical application of these inhibitors due to potential off-target effects and the need for dose optimization.

KEY SCIENTIFIC CONCEPTS OF REVIEW

CDKs regulate key neutrophilic functions, including chemotactic responses, degranulation, NET formation, and apoptosis. Repurposing CDK inhibitors, originally developed for cancer treatment, shows promise in controlling neutrophilic inflammation. Clinical anticancer drugs, palbociclib and ribociclib, have demonstrated efficacy in treating neutrophilic ARDS and psoriasis by targeting off-label pathways, phosphoinositide 3-kinase (PI3K) and phosphodiesterase 4 (PDE4), respectively. While CDK inhibitors offer promising therapeutic benefits, their clinical repurposing requires careful consideration of off-target effects and dose optimization. Further exploration and clinical trials are necessary to ensure their safety and efficacy in treating inflammatory conditions.

Efferocytosis: Unveiling its potential in autoimmune disease and treatment strategies

Efferocytosis is a crucial process whereby phagocytes engulf and eliminate apoptotic cells (ACs). This intricate process can be categorized into four steps: (1) ACs release "find me" signals to attract phagocytes, (2) phagocytosis is directed by "eat me" signals emitted by ACs, (3) phagocytes engulf and internalize ACs, and (4) degradation of ACs occurs. Maintaining immune homeostasis heavily relies on the efficient clearance of ACs, which eliminates self-antigens and facilitates the generation of anti-inflammatory and immunosuppressive signals that maintain immune tolerance. However, any disruptions occurring at any of the efferocytosis steps during apoptosis can lead to a diminished efficacy in removing apoptotic cells. Factors contributing to this inefficiency encompass dysregulation in the release and recognition of "find me" or "eat me" signals, defects in phagocyte surface receptors, bridging molecules, and other signaling pathways. The inadequate clearance of ACs can result in their rupture and subsequent release of self-antigens, thereby promoting immune responses and precipitating the onset of autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, and multiple sclerosis. A comprehensive understanding of the efferocytosis process and its implications can provide valuable insights for developing novel therapeutic strategies that target this process to prevent or treat autoimmune diseases.

Immune cells crosstalk Pathways, and metabolic alterations in Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) presents a challenging progression characterized by lung tissue scarring and abnormal extracellular matrix deposition. This review examines the influence of immune responses, emphasizing their complex role in initiating and perpetuating fibrosis. It highlights how metabolic pathways modulate immune cell function during IPF. Immune cell modulation holds promise in managing pulmonary fibrosis (PF). Inhibiting neutrophil recruitment and monitoring mast cell levels offer insights into PF progression. Low-dose IL-2 therapy and regulation of fibroblast recruitment present potential therapeutic avenues, while the role of innate lymphoid cells (ILC2s) in allergic lung inflammation sheds light on disease mechanisms. The review focuses on metabolic reprogramming's role in shaping immune cell function during IPF progression. While some immune cells use glycolysis for pro-inflammatory responses, others favor fatty acid oxidation for regulatory functions. Targeting specialized pro-resolving lipid mediators (SPMs) presents significant potential for managing fibrotic disorders. Additionally, it highlights the pivotal role of amino acid metabolism in synthesizing serine and glycine as crucial regulators of collagen production and exploring the interconnectedness of lipid metabolism, mitochondrial dysfunction, and adipokines in driving fibrotic processes. Moreover, the review discusses the impact of metabolic disorders such as obesity and diabetes on lung fibrosis. Advocating for a holistic approach, it emphasizes the importance of considering this interplay between immune cell function and metabolic pathways in developing effective and personalized treatments for IPF.

Treatment with lipoxin A 4 improves influenza A infection outcome through macrophage reprogramming, anti-inflammatory and pro-resolutive responses

Objective and design

Here, we evaluated whether a synthetic lipoxin mimetic, designated AT-01-KG, would improve the course of influenza A infection in a murine model.

Treatment

Mice were infected with influenza A/H1N1 and treated with AT-01-KG (1.7 mg/kg/day, i.p.) at day 3 post-infection.

Methods

Mortality rate was assessed up to day 21 and inflammatory parameters were assessed at days 5 and 7.

Results

AT-01-KG attenuated mortality, reducing leukocyte infiltration and lung damage at day 5 and day 7 post-infection. AT-01-KG is a Formyl Peptide Receptor 2 (designated FPR2/3 in mice) agonist, and the protective responses were not observed in FPR2/3 -/- animals. In mice treated with LXA4 (50mg/kg/day, i.p., days 3-6 post-infection), at day 7, macrophage reprogramming was observed, as seen by a decrease in classically activated macrophages and an increase in alternatively activated macrophages in the lungs. Furthermore, the number of apoptotic cells and cells undergoing efferocytosis was increased in the lavage of treated mice. Treatment also modulated the adaptive immune response, increasing the number of anti-inflammatory T cells (Th2) and regulatory T (Tregs) cells in the lungs of the treated mice.

Conclusions

Therefore, treatment with a lipoxin A4 analog was beneficial in a model of influenza A infection in mice. The drug decreased inflammation and promoted resolution and beneficial immune responses, suggesting it may be useful in patients with severe influenza.

Relationship between neutrophil to lymphocyte ratio and diabetic peripheral neuropathy: a systematic review and meta-analysis

BACKGROUND

The present study aims to review the existing scientific literature on the role of neutrophil to lymphocyte ratio (NLR) in diabetic peripheral neuropathy (DPN) to perform a meta-analysis on the available data.

METHODS

The electronic repositories Web of Science, PubMed, and Scopus were systematically explored starting from their establishment up until June 9, 2022.

RESULTS

Fifteen articles were included in the meta-analysis after multiple screening according to the PRISMA guidelines. The combined findings indicated that individuals with DPN had higher levels of NLR in comparison to those without DPN (SMD = 0.61; CI 95% = 0.40-0.81, p < 0.001). In the subgroup assessment based on ethnicity, it was observed that diabetic patients with DPN exhibited increased NLR levels in contrast to those without DPN in studies conducted in India (SMD = 1.30; CI 95% = 0.37-2.24, p = 0.006) and East Asia (SMD = 0.53; CI 95% = 0.34-0.73, p < 0.001) but not in studies conducted in Turkey (SMD = 0.30; CI 95% = - 0.06-0.67, p = 0.104) and Egypt (SMD = 0.34; CI 95% = -0.14-0.82, p = 0.165). The pooled sensitivity of NLR was 0.67 (95% CI = 0.49-0.81), and the pooled specificity was 0.70 (95% CI, 0.56-0.81). The pooled positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio (DOR) of NLR were 2.30 (95% CI = 1.71-3.09), 0.45 (95%CI = 0.30-0.67), and 5.06 (95% CI = 3.16-8.12), respectively.

CONCLUSION

NLR serves as a distinct marker of inflammation, and its rise in cases of DPN suggests an immune system imbalance playing a role in the development of the disease.

Lipoxin-mediated signaling: ALX/FPR2 interaction and beyond

In the aftermath of tissue injury or infection, an efficient resolution mechanism is crucial to allow tissue healing and preserve appropriate organ functioning. Pro-resolving bioactive lipids prevent uncontrolled inflammation and its consequences. Among these mediators, lipoxins were the first described and their pro-resolving actions have been mainly described in immune cells. They exert their actions mostly through formyl-peptide receptor 2 (ALX/FPR2 receptor), a G-protein-coupled receptor whose biological function is tremendously complex, primarily due to its capacity to mediate variable cellular responses. Moreover, lipoxins can also interact with alternative receptors like the cytoplasmic aryl hydrocarbon receptor, the cysteinyl-leukotrienes receptors or GPR32, triggering different intracellular signaling pathways. The available information about this complex response mediated by lipoxins is addressed in this review, going over the different mechanisms used by these molecules to stop the inflammatory reaction and avoid the development of dysregulated and chronic pathologies.

Immunomodulation for Tissue Repair and Regeneration

Various immune cells participate in repair and regeneration following tissue injury or damage, orchestrating tissue inflammation and regeneration processes. A deeper understanding of the immune system's involvement in tissue repair and regeneration is critical for the development of successful reparatory and regenerative strategies. Here we review recent technologies that facilitate cell-based and biomaterial-based modulation of the immune systems for tissue repair and regeneration. First, we summarize the roles of various types of immune cells in tissue repair. Second, we review the principle, examples, and limitations of regulatory T (Treg) cell-based therapy, a representative cell-based immunotherapy. Finally, we discuss biomaterial-based immunotherapy strategies that aim to modulate immune cells using various biomaterials for tissue repair and regeneration.

Neutrophils as a potential therapeutic target in Alzheimer's disease

Alzheimer's disease (AD) is the leading cause of dementia in the United States. Sporadic or late-onset AD remains incompletely understood, with age as the current greatest risk factor. Inflammation in general and neutrophils, a potent mediator of inflammation, have been shown to exacerbate AD associated dementia. This review explores the latest research on neutrophils in AD mouse models and in human cohort studies and discusses current gaps in research and needs for future studies. AD mouse models have shown neutrophil chemotactic migration towards amyloid beta plaques in the brain. Capillary blood flow stalling decreases blood perfusion to associated brain regions and mouse studies have demonstrated that anti-Ly6G antibodies lead to a decrease in capillary blood flow stalling and memory improvement. Several recent transcriptomic studies of blood and brain tissue from persons with AD have shown an upregulation in neutrophil-related genes, and studies have demonstrated neutrophil involvement in brain capillary adhesion, blood brain barrier breaching, myeloperoxidase release, and the propensity for neutrophil extracellular trap release in AD. Neutrophil-derived inflammation and regulation are a potential potent novel therapeutic target for AD progression. Future studies should further investigate neutrophil functionality in AD. In addition, other aspects of AD that may impact neutrophils including the microbiome and the APOE4 allele should be studied.

Blocking the HGF-MET pathway induces resolution of neutrophilic inflammation by promoting neutrophil apoptosis and efferocytosis

Inflammation resolution is an active process that involves cellular events such as apoptosis and efferocytosis, which are key steps in the restoration of tissue homeostasis. Hepatocyte growth factor (HGF) is a growth factor mostly produced by mesenchymal-origin cells and has been described to act via MET receptor tyrosine kinase. The HGF/MET axis is essential for determining the progression and severity of inflammatory and immune-mediated disorders. Here, we investigated the effect of blocking the HGF/MET signalling pathway by PF-04217903 on the resolution of established models of neutrophilic inflammation. In a self-resolving model of gout induced by MSU crystals, HGF expression on periarticular tissue peaked at 12 h, the same time point that neutrophils reach their maximal accumulation in the joints. The HGF/MET axis was activated in this model, as demonstrated by increased levels of MET phosphorylation in neutrophils (Ly6G⁺ cells). In addition, the number of neutrophils was reduced in the knee exudate after PF-04217903 treatment, an effect accompanied by increased neutrophil apoptosis and efferocytosis and enhanced expression of Annexin A1, a key molecule for inflammation resolution. Reduced MPO activity, IL-1β and CXCL1 levels were also observed in periarticular tissue. Importantly, PF-04217903 reduced the histopathological score and hypernociceptive response. Similar findings were obtained in LPS-induced neutrophilic pleurisy. In human neutrophils, the combined use of LPS and HGF increased MET phosphorylation and provided a prosurvival signal, whereas blocking MET with PF-04217903 induced caspase-dependent neutrophil apoptosis. Taken together, these data demonstrate that blocking HGF/MET signalling may be a potential therapeutic strategy for inducing the resolution of neutrophilic inflammatory responses.

Cardiac repair after myocardial infarction: A two-sided role of inflammation-mediated

Myocardial infarction is the leading cause of death and disability worldwide, and the development of new treatments can help reduce the size of myocardial infarction and prevent adverse cardiovascular events. Cardiac repair after myocardial infarction can effectively remove necrotic tissue, induce neovascularization, and ultimately replace granulation tissue. Cardiac inflammation is the primary determinant of whether beneficial cardiac repair occurs after myocardial infarction. Immune cells mediate inflammatory responses and play a dual role in injury and protection during cardiac repair. After myocardial infarction, genetic ablation or blocking of anti-inflammatory pathways is often harmful. However, enhancing endogenous anti-inflammatory pathways or blocking endogenous pro-inflammatory pathways may improve cardiac repair after myocardial infarction. A deficiency of neutrophils or monocytes does not improve overall cardiac function after myocardial infarction but worsens it and aggravates cardiac fibrosis. Several factors are critical in regulating inflammatory genes and immune cells' phenotypes, including DNA methylation, histone modifications, and non-coding RNAs. Therefore, strict control and timely suppression of the inflammatory response, finding a balance between inflammatory cells, preventing excessive tissue degradation, and avoiding infarct expansion can effectively reduce the occurrence of adverse cardiovascular events after myocardial infarction. This article reviews the involvement of neutrophils, monocytes, macrophages, and regulatory T cells in cardiac repair after myocardial infarction. After myocardial infarction, neutrophils are the first to be recruited to the damaged site to engulf necrotic cell debris and secrete chemokines that enhance monocyte recruitment. Monocytes then infiltrate the infarct site and differentiate into macrophages and they release proteases and cytokines that are harmful to surviving myocardial cells in the pre-infarct period. As time progresses, apoptotic neutrophils are cleared, the recruitment of anti-inflammatory monocyte subsets, the polarization of macrophages toward the repair phenotype, and infiltration of regulatory T cells, which secrete anti-inflammatory factors that stimulate angiogenesis and granulation tissue formation for cardiac repair. We also explored how epigenetic modifications regulate the phenotype of inflammatory genes and immune cells to promote cardiac repair after myocardial infarction. This paper also elucidates the roles of alarmin S100A8/A9, secreted frizzled-related protein 1, and podoplanin in the inflammatory response and cardiac repair after myocardial infarction.

“Rogue” neutrophil-subset [DEspR+CD11b+/CD66b+] immunotype is an actionable therapeutic target for neutrophilic inflammation-mediated tissue injury – studies in human, macaque and rat LPS-inflammation models

Background and objective

The correlation (Rs > 0.7) of neutrophils expressing the dual endothelin1/signal peptide receptor (DEspR+CD11b+/CD66b+) with severity of hypoxemia (SF-ratio) and multi-organ failure (SOFA-score) in patients with acute respiratory distress syndrome (ARDS) suggest the hypothesis that the DEspR+ neutrophil-subset is an actionable therapeutic target in ARDS. To test this hypothesis, we conducted in vivo studies to validate DEspR+ neutrophil-subset as therapeutic target and test efficacy of DEspR-inhibition in acute neutrophilic hyperinflammation models.

Methods

We performed tests in lipopolysaccharide (LPS)-induced acute neutrophilic inflammation in three species – human, rhesus macaque, rat – with increasing dose-dependent severity. We measured DEspR+CD66b+ neutrophils in bronchoalveolar lavage fluid (BALF) in healthy volunteers (HVs) 24-hours after segmental LPS-challenge by ChipCytometry, and DEspR+CD11b+ neutrophils in whole blood and BALF in an LPS-induced transient acute lung injury (ALI) model in macaques. We determined anti-DEspR antibody efficacy in vivo in LPS-ALI macaque model and in high-mortality LPS-induced encephalopathy in hypertensive rats.

Results

ChipCytometry detected increased BALF total neutrophil and DEspR+CD66b+ neutrophil counts after segmental LPS-challenge compared to baseline (P =0.034), as well as increased peripheral neutrophil counts and neutrophil-lymphocyte ratio (NLR) compared to pre-LPS level (P <0.05). In the LPS-ALI macaque model, flow cytometry detected increased DEspR+ and DEspR[-] neutrophils in BALF, which was associated with moderate-severe hypoxemia. After determining pharmacokinetics of single-dose anti-DEspR[hu6g8] antibody, one-time pre-LPS anti-DEspR treatment reduced hypoxemia (P =0.03) and neutrophil influx into BALF (P =0.0001) in LPS-ALI vs vehicle mock-treated LPS-ALI macaques. Ex vivo live cell imaging of macaque neutrophils detected greater “intrinsic adhesion to hard-surface” in DEspR+ vs DEspR[-] neutrophils (P <0.001). Anti-DEspR[hu6g8] antibody abrogated intrinsic high adhesion in DEspR+ neutrophils, but not in DEspR[-] neutrophils (P <0.001). In the LPS-encephalopathy rat model, anti-DEspR[10a3] antibody treatment increased median survival (P =0.0007) and exhibited brain target engagement and bioeffects.

Conclusion

Detection of increased DEspR+ neutrophil-subset in human BALF after segmental LPS-challenge supports the correlation of circulating DEspR+ neutrophil counts with severity measure (SOFA-score) in ARDS. Efficacy and safety of targeted inhibition of DEspR+CD11b+ neutrophil-subset in LPS-induced transient-ALI and high-mortality encephalopathy models identify a potential therapeutic target for neutrophil-mediated secondary tissue injury.

Inflammatory Response to Regulated Cell Death in Gout and Its Functional Implications

Gout, a chronic inflammatory arthritis disease, is characterized by hyperuricemia and caused by interactions between genetic, epigenetic, and metabolic factors. Acute gout symptoms are triggered by the inflammatory response to monosodium urate crystals, which is mediated by the innate immune system and immune cells (e.g., macrophages and neutrophils), the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome activation, and pro-inflammatory cytokine (e.g., IL-1β) release. Recent studies have indicated that the multiple programmed cell death pathways involved in the inflammatory response include pyroptosis, NETosis, necroptosis, and apoptosis, which initiate inflammatory reactions. In this review, we explore the correlation and interactions among these factors and their roles in the pathogenesis of gout to provide future research directions and possibilities for identifying potential novel therapeutic targets and enhancing our understanding of gout pathogenesis.

Study of the immunologic response of marine-derived collagen and gelatin extracts for tissue engineering applications

The host immunologic response to a specific material is a critical aspect when considering it for clinical implementation. Collagen and gelatin extracted from marine sources have been proposed as biomaterials for tissue engineering applications, but there is a lack of information in the literature about their immunogenicity. In this work, we evaluated the immune response to collagen and/or gelatin from blue shark and codfish, previously extracted and characterized. After endotoxin evaluation, bone marrow-derived macrophages were exposed to the materials and a panel of pro- and anti-inflammatory cytokines were evaluated both for protein quantification and gene expression. Then, the impact of those materials in the host was evaluated through peritoneal injection in C57BL/6 mice. The results suggested shark collagen as the less immunogenic material, inducing low expression of pro-inflammatory cytokines as well as inducible nitric oxide synthase (encoded by Nos2) and high expression of Arginase 1 (encoded by Arg1). Although shark gelatin appeared to be the material with higher pro-inflammatory expression, it also presents a high expression of IL-10 (anti-inflammatory cytokine) and Arginase (both markers for M2-like macrophages). When injected in the peritoneal cavity of mice, our materials demonstrated a transient recruitment of neutrophil, being almost non-existent after 24 hours of injection. Based on these findings, the studied collagenous materials can be considered interesting biomaterial candidates for regenerative medicine as they may induce an activation of the M2-like macrophage population, which is involved in suppressing the inflammatory processes promoting tissue remodeling. STATEMENT OF SIGNIFICANCE: Marine-origin biomaterials are emerging in the biomedical arena, namely the ones based in marine-derived collagen/gelatin proposed as cell templates for tissue regeneration. Nevertheless, although the major cause of implant rejection in clinical practice is the host's negative immune response, there is a lack of information in the literature about the immunological impact of these marine collagenous materials. This work aims to contribute with knowledge about the immunologic response to collagen/gelatin extracted from blue shark and codfish skins. The results demonstrated that despite some differences observed, all the materials can induce a macrophage phenotype related with anti-inflammation resolution and then act as immuno-modulators and anti-inflammatory inducible materials.

In Vivo Efficacy of Neutrophil-Mediated Bone Regeneration Using a Rabbit Calvarial Defect Model

Reconstruction of bone due to surgical removal or disease-related bony defects is a clinical challenge. It is known that the immune system exerts positive immunomodulatory effects on tissue repair and regeneration. In this study, we evaluated the in vivo efficacy of autologous neutrophils on bone regeneration using a rabbit calvarial defect model. Methods: Twelve rabbits, each with two surgically created calvarial bone defects (10 mm diameter), were randomly divided into two groups; (i) single application of neutrophils (SA-NP) vs. SA-NP control, and (ii) repetitive application of neutrophils (RA-NP) vs. RA-NP control. The animals were euthanized at 4 and 8 weeks post-operatively and the treatment outcomes were evaluated by micro-computed tomography, histology, and histomorphometric analyses. Results: The micro-CT analysis showed a significantly higher bone volume fraction (bone volume/total volume) in the neutrophil-treated groups, i.e., median interquartile range (IQR) SA-NP (18) and RA-NP (24), compared with the untreated controls, i.e., SA-NP (7) and RA-NP (14) at 4 weeks (p < 0.05). Similarly, new bone area fraction (bone area/total area) was significantly higher in neutrophil-treated groups at 4 weeks (p < 0.05). Both SA-NP and RA-NP had a considerably higher bone volume and bone area at 8 weeks, although the difference was not statistically significant. In addition, immunohistochemical analysis at 8 weeks revealed a higher expression of osteocalcin in both SA-NP and RA-NP groups. Conclusions: The present study provides first hand evidence that autologous neutrophils may have a positive effect on promoting new bone formation. Future studies should be performed with a larger sample size in non-human primate models. If proven feasible, this new promising strategy could bring clinical benefits for bone defects to the field of oral and maxillofacial surgery.

Macrophages: The Good, the Bad, and the Gluttony

Macrophages are dynamic cells that play critical roles in the induction and resolution of sterile inflammation. In this review, we will compile and interpret recent findings on the plasticity of macrophages and how these cells contribute to the development of non-infectious inflammatory diseases, with a particular focus on allergic and autoimmune disorders. The critical roles of macrophages in the resolution of inflammation will then be examined, emphasizing the ability of macrophages to clear apoptotic immune cells. Rheumatoid arthritis (RA) is a chronic autoimmune-driven spectrum of diseases where persistent inflammation results in synovial hyperplasia and excessive immune cell accumulation, leading to remodeling and reduced function in affected joints. Macrophages are central to the pathophysiology of RA, driving episodic cycles of chronic inflammation and tissue destruction. RA patients have increased numbers of active M1 polarized pro-inflammatory macrophages and few or inactive M2 type cells. This imbalance in macrophage homeostasis is a main contributor to pro-inflammatory mediators in RA, resulting in continual activation of immune and stromal populations and accelerated tissue remodeling. Modulation of macrophage phenotype and function remains a key therapeutic goal for the treatment of this disease. Intriguingly, therapeutic intervention with glucocorticoids or other DMARDs promotes the re-polarization of M1 macrophages to an anti-inflammatory M2 phenotype; this reprogramming is dependent on metabolic changes to promote phenotypic switching. Allergic asthma is associated with Th2-polarised airway inflammation, structural remodeling of the large airways, and airway hyperresponsiveness. Macrophage polarization has a profound impact on asthma pathogenesis, as the response to allergen exposure is regulated by an intricate interplay between local immune factors including cytokines, chemokines and danger signals from neighboring cells. In the Th2-polarized environment characteristic of allergic asthma, high levels of IL-4 produced by locally infiltrating innate lymphoid cells and helper T cells promote the acquisition of an alternatively activated M2a phenotype in macrophages, with myriad effects on the local immune response and airway structure. Targeting regulators of macrophage plasticity is currently being pursued in the treatment of allergic asthma and other allergic diseases. Macrophages promote the re-balancing of pro-inflammatory responses towards pro-resolution responses and are thus central to the success of an inflammatory response. It has long been established that apoptosis supports monocyte and macrophage recruitment to sites of inflammation, facilitating subsequent corpse clearance. This drives resolution responses and mediates a phenotypic switch in the polarity of macrophages. However, the role of apoptotic cell-derived extracellular vesicles (ACdEV) in the recruitment and control of macrophage phenotype has received remarkably little attention. ACdEV are powerful mediators of intercellular communication, carrying a wealth of lipid and protein mediators that may modulate macrophage phenotype, including a cargo of active immune-modulating enzymes. The impact of such interactions may result in repair or disease in different contexts. In this review, we will discuss the origin, characterization, and activity of macrophages in sterile inflammatory diseases and the underlying mechanisms of macrophage polarization via ACdEV and apoptotic cell clearance, in order to provide new insights into therapeutic strategies that could exploit the capabilities of these agile and responsive cells.

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.

Role of specialized pro-resolving lipid mediators in pulmonary inflammation diseases: mechanisms and development

Inflammation is an essential mechanism of various diseases. The development and resolution of inflammation are complex immune-modulation processes which induce the involvement of various types of immune cells. Specialized pro-resolving lipid mediators (SPMs) have been demonstrated to be signaling molecules in inflammation. SPMs are involved in the pathophysiology of different diseases, especially respiratory diseases, including asthma, pneumonia, and chronic obstructive pulmonary disease. All of these diseases are related to the inflammatory response and its persistence. Therefore, a deeper understanding of the mechanisms and development of inflammation in respiratory disease, and the roles of the SPM family in the resolution process, might be useful in the quest for novel therapies and preventive measures for pulmonary diseases.

The Predictive Value of Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio Levels of Diabetic Peripheral Neuropathy

Objective

This study was designed to assess the levels of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in diabetes patients to determine their prognostic value in predicting the disease of diabetic peripheral neuropathy (DPN).

Methods

We recruited 225 diabetes cases from the department of endocrinology of Anhui Provincial Hospital from August 2018 to October 2019. A total of 103 patients without diabetic peripheral neuropathy (DPN) were followed up for 18 months, and the number of patients of newly diagnosed DPN was counted. According to the results of neuroelectrophysiological examination, these patients were divided into the diabetes mellitus (DM) without DPN group and the DM with DPN group. The general information and results of blood samples were collected. The collected data were compared between groups, and the receiver operating characteristic curve (ROC) was drawn. The follow-up data were compared between groups and Binary Logistic regression analysis was performed.

Results

Patients with DPN shared distinct characteristics. For example, the patients were older, and had higher levels of inflammatory indicators (ie, levels of PLR and NLR), and lower level of indirect bilirubin, compared with patients without DPN. According to the receiver operating characteristic curve analysis, for type 1 diabetes, PLR showed the highest area under the curve (0.753). For type 2 diabetes, NLR showed the highest AUC of 0.602. For the follow-up results, patients with newly diagnosed DPN bad higher NLR level.

Conclusion

If patients of type 1 and type 2 diabetes are combined with elevated level of PLR and NLR, respectively, they are more likely complicated with DPN. NLR and PLR could be used as predictors to help clinicians screening for DPN in different types of diabetes. For type 1 diabetes, if patients who were without DPN had higher NLR level, the risk of developing DPN in the future will be greatly increased.

Importance of hematological parameters for micro- and macrovascular outcomes in patients with type 2 diabetes: the Rio de Janeiro type 2 diabetes cohort study

Background

The prognostic importance of several hematological parameters has been scarcely investigated in type 2 diabetes. So, we aimed to evaluate their prognostic importance for development of complications in a cohort of type 2 diabetes.

Methods

In a prospective study, 689 individuals with type 2 diabetes had blood red cell, platelet and leukocyte parameters obtained at baseline. Multivariate Cox analyses examined the associations between several hematological parameters (including neutrophyl-to-lymphocyte, lymphocyte-to-monocyte, platelet-to-lymphocyte, and monocyte-to-HDL ratios) and the occurrence of microvascular (retina, renal and peripheral neuropathy) and cardiovascular complications (total cardiovascular events [CVEs], and major adverse CVEs [MACEs]), and all-cause and cardiovascular mortality. Improvements in risk discrimination were assessed by C-statistics and Integrated Discrimination Improvement (IDI) index.

Results

During a median follow-up of 10.5 years, 212 patients had a CVE (174 MACEs), 264 patients died (131 cardiovascular deaths); 206 had a renal, 161 a retinopathy and 179 patients had a neuropathy outcome. In multivariate-adjusted analyses, the lymphocytes count and lymphocyte-to-monocyte ratio were protective (hazard ratios [HRs]: 0.77 and 0.72, respectively), whereas the neutrophyl-to-lymphocyte and platelet-to-lymphocyte ratios were associated with increased risks (HRs: 1.19 and 1.17) for all-cause mortality. For cardiovascular mortality, the monocytes count, the neutrophyl-to-lymphocyte and monocyte-to-HDL ratios were associated with increased risks and the lymphocyte-to-monocyte ratio was protective. Higher lymphocyte-to-monocyte ratio was protective for renal failure outcome. However, none of them improved risk discrimination.

Conclusions

Low lymphocytes count and leukocyte ratios that mainly included lymphocytes were predictors of macrovascular complications and mortality in individuals with type 2 diabetes. However, they did not improve risk prediction over traditional risk factors.

Role of Neutrophils in Cardiac Injury and Repair Following Myocardial Infarction

Neutrophils are first-line responders of the innate immune system. Following myocardial infarction (MI), neutrophils are quickly recruited to the ischemic region, where they initiate the inflammatory response, aiming at cleaning up dead cell debris. However, excessive accumulation and/or delayed removal of neutrophils are deleterious. Neutrophils can promote myocardial injury by releasing reactive oxygen species, granular components, and pro-inflammatory mediators. More recent studies have revealed that neutrophils are able to form extracellular traps (NETs) and produce extracellular vesicles (EVs) to aggravate inflammation and cardiac injury. On the contrary, there is growing evidence showing that neutrophils also exert anti-inflammatory, pro-angiogenic, and pro-reparative effects, thus facilitating inflammation resolution and cardiac repair. In this review, we summarize the current knowledge on neutrophils’ detrimental roles, highlighting the role of recently recognized NETs and EVs, followed by a discussion of their beneficial effects and molecular mechanisms in post-MI cardiac remodeling. In addition, emerging concepts about neutrophil diversity and their modulation of adaptive immunity are discussed.

CD300a contributes to the resolution of articular inflammation triggered by MSU crystals by controlling neutrophil apoptosis

Gout is an inflammatory disease triggered by deposition of monosodium urate (MSU) crystals in the joints, resulting in high neutrophil influx and pain. Here, we studied the role of the inhibitory receptor CD300a in the resolution process in a murine model of gout. We found increased CD300a expression on neutrophils emigrated to the joint. When compared to WT mice, CD300a^-/- mice had persistent neutrophil influx till 24 hr after MSU injection. This was associated with increased concentration of IL-1β and greater tissue damage in the joints of CD300a^-/- mice. There was an increase in the percentage of apoptotic neutrophils in the synovial lavage of WT mice, as compared to CD300a^-/- mice. This difference was reflected in the decline of efferocytic events in the synovial cavity of CD300a^-/- mice 24 hr after MSU injection. A CD300a agonistic antibody was shown, for the first time, to increase apoptosis of human neutrophils, and this was associated with cleavage of caspase-8. In conclusion, our results reveal an important role of CD300a in the control of leucocyte infiltration, IL-1β production and caspase-8 cleavage in neutrophils, contributing to the resolution of inflammation triggered by MSU injection.

Molecular Mechanisms for Regulation of Neutrophil Apoptosis under Normal and Pathological Conditions

Neutrophils are one of the main cells of innate immunity that perform a key effector and regulatory function in the development of the human inflammatory response. Apoptotic forms of neutrophils are important for regulating the intensity of inflammation and restoring tissue homeostasis. This review summarizes current data on the molecular mechanisms of modulation of neutrophil apoptosis by the main regulatory factors of the inflammatory response-cytokines, integrins, and structural components of bacteria. Disturbances in neutrophil apoptosis under stress are also considered, molecular markers of changes in neutrophil lifespan associated with various diseases and pathological conditions are presented, and data on pharmacological agents for modulating apoptosis as potential therapeutics are also discussed.

The Neutrophil: Constant Defender and First Responder

The role of polymorphonuclear neutrophils (PMNs) in biology is often recognized during pathogenesis associated with PMN hyper- or hypo-functionality in various disease states. However, in the vast majority of cases, PMNs contribute to resilience and tissue homeostasis, with continuous PMN-mediated actions required for the maintenance of health, particularly in mucosal tissues. PMNs are extraordinarily well-adapted to respond to and diminish the damaging effects of a vast repertoire of infectious agents and injurious processes that are encountered throughout life. The commensal biofilm, a symbiotic polymicrobial ecosystem that lines the mucosal surfaces, is the first line of defense against pathogenic strains that might otherwise dominate, and is therefore of critical importance for health. PMNs regularly interact with the commensal flora at the mucosal tissues in health and limit their growth without developing an overt inflammatory reaction to them. These PMNs exhibit what is called a para-inflammatory phenotype, and have reduced inflammatory output. When biofilm growth and makeup are disrupted (i.e., dysbiosis), clinical symptoms associated with acute and chronic inflammatory responses to these changes may include pain, erythema and swelling. However, in most cases, these responses indicate that the immune system is functioning properly to re-establish homeostasis and protect the status quo. Defects in this healthy everyday function occur as a result of PMN subversion by pathological microbial strains, genetic defects or crosstalk with other chronic inflammatory conditions, including cancer and rheumatic disease, and this can provide some avenues for therapeutic targeting of PMN function. In other cases, targeting PMN functions could worsen the disease state. Certain PMN-mediated responses to pathogens, for example Neutrophil Extracellular Traps (NETs), might lead to undesirable symptoms such as pain or swelling and tissue damage/fibrosis. Despite collateral damage, these PMN responses limit pathogen dissemination and more severe damage that would otherwise occur. New data suggests the existence of unique PMN subsets, commonly associated with functional diversification in response to particular inflammatory challenges. PMN-directed therapeutic approaches depend on a greater understanding of this diversity. Here we outline the current understanding of PMNs in health and disease, with an emphasis on the positive manifestations of tissue and organ-protective PMN-mediated inflammation.

Biological responses to physicochemical properties of biomaterial surface

Biomedical scientists use chemistry-driven processes found in nature as an inspiration to design biomaterials as promising diagnostic tools, therapeutic solutions, or tissue substitutes. While substantial consideration is devoted to the design and validation of biomaterials, the nature of their interactions with the surrounding biological microenvironment is commonly neglected. This gap of knowledge could be owing to our poor understanding of biochemical signaling pathways, lack of reliable techniques for designing biomaterials with optimal physicochemical properties, and/or poor stability of biomaterial properties after implantation. The success of host responses to biomaterials, known as biocompatibility, depends on chemical principles as the root of both cell signaling pathways in the body and how the biomaterial surface is designed. Most of the current review papers have discussed chemical engineering and biological principles of designing biomaterials as separate topics, which has resulted in neglecting the main role of chemistry in this field. In this review, we discuss biocompatibility in the context of chemistry, what it is and how to assess it, while describing contributions from both biochemical cues and biomaterials as well as the means of harmonizing them. We address both biochemical signal-transduction pathways and engineering principles of designing a biomaterial with an emphasis on its surface physicochemistry. As we aim to show the role of chemistry in the crosstalk between the surface physicochemical properties and body responses, we concisely highlight the main biochemical signal-transduction pathways involved in the biocompatibility complex. Finally, we discuss the progress and challenges associated with the current strategies used for improving the chemical and physical interactions between cells and biomaterial surface.

Liang-Ge-San, a classic traditional Chinese medicine formula, attenuates acute inflammation in zebrafish and RAW 264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Liang-Ge-San (LGS) is a traditional Chinese medicine formula that commonly used in acute inflammatory diseases. However, the anti-inflammatory effects and the underlying mechanisms of LGS are not fully studied.

AIM OF THE STUDY

This study aims to investigate the anti-inflammatory activity and explore the underlying mechanisms of LGS in zebrafish and cell inflammation models.

MATERIALS AND METHODS

LPS-induced zebrafish inflammation model was established by LPS-yolk microinjection. The protective effect of LGS on zebrafish injected with LPS was observed using survival analysis. Infiltration of inflammatory cells was determined by H&E staining assay. Expression levels of key inflammatory cytokines TNF-α and IL-6 were measured by q-PCR assay. Recruitment of neutrophils and macrophages were observed by fluorescence microscopy, SB staining and NR staining. In vitro anti-inflammatory effects of LGS were evaluated on LPS-stimulated RAW 264.7 cells. The generation of IL-6 and TNF-α was detected by ELISA. The protein expression levels of JNK, p-JNK (Thr183/Tyr185), Nur77 and p-Nur77 (Ser351) were determined by Western blotting. Finally, two additional inflammatory models in zebrafish, which were induced by CuSO₄ or tail fin injury, were also established and the recruitment of neutrophils and macrophages were observed for the determination of the anti-inflammatory activity of LGS.

RESULTS

LGS protected zebrafish against LPS-induced death and dose-dependently inhibited LPS-induced acute inflammatory response in zebrafish, as indicated by increased survival rate, reduced infiltration of inflammatory cells, decreased recruitment of macrophages and neutrophils, and downregulated expression levels of TNF-α and IL-6. Additionally, LGS inhibited the secretion of TNF-α and IL-6, increased the expression of Nur77, and reduced the expression of p-Nur77 (Ser351) and p-JNK (Thr183/Tyr185) in LPS-stimulated RAW 264.7 cells. The anti-inflammatory action of LGS was also observed in another two zebrafish inflammation models, which was supported by the inhibition on neutrophils and macrophages recruitment.

CONCLUSION

The present study demonstrates that LGS possesses anti-inflammatory activity in zebrafish inflammation models and LPS-stimulated RAW 264.7 cells, which is related to the inhibition on p-JNK and p-Nur77. This finding provides a pharmacological basis for LGS in the control of inflammatory disorder.

Protective role of curcumin against lipopolysaccharide-induced inflammation and apoptosis in human neutrophil

Background

Sepsis, an uncontrolled host response to infection, may be life-threatening organ injury. Neutrophils play a critical role in regulation of host immune response to infection. Curcumin, known as a spice and food coloring agent, possesses anti-inflammatory properties. In this study, we investigated the effects of curcumin on lipopolysaccharide (LPS)-induced neutrophil activation with its signaling pathways.

Methods

Isolated human neutrophils were incubated without or with LPS and curcumin, and the expression of pro-inflammatory cytokines, such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and IL-8 were assessed by enzyme-linked immunosorbent assays. The expression of mitogen-activated protein kinases such as p38, extracellularsignal-regulated kinase (ERK)1/2, and c-Jun N-terminal kinase (JNK) were evaluated by Western blot analysis. Neutrophil apoptosis was also measured by fluorescence-activated cell sorting (annexin V/propidium iodide) in LPS-stimulated neutrophils under treatment with curcumin.

Results

Curcumin attenuated expression of TNF-α, IL-6, and IL-8 and the phosphorylation levels of p38 and JNK, but not ERK1/2, in LPS-stimulated neutrophils. Additionally, curcumin restored the delayed neutrophil apoptosis by LPS-stimulated neutrophils(19.7 ± 3.2 to 38.2 ± 0.5%, P < 0.05).

Conclusions

Our results reveal the underlying mechanism of how curcumin attenuate neutrophil activation and suggest potential clinic applications of curcumin supplementation for patients with severe sepsis and septic shock. Additional clinical studies are required to confirm these in vitro findings.

Neutrophil Subsets in Periodontal Health and Disease: A Mini Review

Neutrophils are amongst the most abundant immune cells within the periodontal tissues and oral cavity. As innate immune cells, they are first line defenders at the tooth-mucosa interface, and can perform an array of different functions. With regard to these, it has been observed over many years that neutrophils are highly heterogeneous in their behavior. Therefore, it has been speculated that neutrophils, similarly to other leukocytes, exist in distinct subsets. Several studies have investigated different markers of neutrophils in oral health and disease in recent years in order to define potential cell subsets and their specific tasks. This research was inspired by recent advancements in other fields of medicine in this field. The aim of this review is to give an overview of the current evidence regarding the existence and presence of neutrophil subsets and their possible functions, specifically in the context of periodontitis, gingivitis, and periodontal health.

Phenolic Compounds Isolated from Calea uniflora Less. Promote Anti-Inflammatory and Antioxidant Effects in Mice Neutrophils (Ex Vivo) and in Mice Pleurisy Model (In Vivo)

The literature shows that phenolic compounds possess important antioxidant and anti-inflammatory activities; however, the mechanism underlying these effects is not elucidated yet. The genus Calea is used in folk medicine to treat rheumatism, respiratory diseases, and digestive problems. In this context, some phenolic compounds were isolated with high purity from Calea uniflora Less. and identified as noreugenin (NRG) and α-hydroxy-butein (AH-BU). The aim of this study was to analyze the effect of these compounds on cell viability, the activity of myeloperoxidase (MPO), and apoptosis of mouse neutrophils using ex vivo tests. Furthermore, the effect of these compounds on the cytokines, interleukin 1 beta (IL-1β), interleukin 17A (IL-17A), and interleukin 10 (IL-10), and oxidative stress was investigated by analyzing lipid peroxidation (the concentration of thiobarbituric acid reactive substances (TBARS)) and activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST), using a murine model of neutrophilic inflammation. The NRG and AH-BU reduce MPO activity and increase neutrophil apoptosis (p < 0.05). These compounds reduced the generation of oxygen reactive species and IL-1β and IL-17A levels but increased IL-10 levels (p < 0.05). This study demonstrated that NRG and AH-BU show a significant anti-inflammatory effect by inhibiting the MPO activity and increasing neutrophil apoptosis in primary cultures of mouse neutrophils. These effects were at least partially associated with blocking reactive species generation, inhibiting IL-1β and IL-17A, and increasing IL-10 levels.

Increased mucosal neutrophil survival is associated with altered microbiota in HIV infection

Gastrointestinal (GI) mucosal dysfunction predicts and likely contributes to non-infectious comorbidities and mortality in HIV infection and persists despite antiretroviral therapy. However, the mechanisms underlying this dysfunction remain incompletely understood. Neutrophils are important for containment of pathogens but can also contribute to tissue damage due to their release of reactive oxygen species and other potentially harmful effector molecules. Here we used a flow cytometry approach to investigate increased neutrophil lifespan as a mechanism for GI neutrophil accumulation in chronic, treated HIV infection and a potential role for gastrointestinal dysbiosis. We report that increased neutrophil survival contributes to neutrophil accumulation in colorectal biopsy tissue, thus implicating neutrophil lifespan as a new therapeutic target for mucosal inflammation in HIV infection. Additionally, we characterized the intestinal microbiome of colorectal biopsies using 16S rRNA sequencing. We found that a reduced Lactobacillus: Prevotella ratio associated with neutrophil survival, suggesting that intestinal bacteria may contribute to GI neutrophil accumulation in treated HIV infection. Finally, we provide evidence that Lactobacillus species uniquely decrease neutrophil survival and neutrophil frequency in vitro, which could have important therapeutic implications for reducing neutrophil-driven inflammation in HIV and other chronic inflammatory conditions.

Perivascular delivery of resolvin D1 inhibits neointimal hyperplasia in a rabbit vein graft model

OBJECTIVE

Inflammation is a key driver of excessive neointimal hyperplasia within vein grafts. Recent work demonstrates that specialized proresolving lipid mediators biosynthesized from omega-3 polyunsaturated fatty acids, such as resolvin D1 (RvD1), actively orchestrate the process of inflammation resolution. We investigated the effects of local perivascular delivery of RvD1 in a rabbit vein graft model.

METHODS

Ipsilateral jugular veins were implanted as carotid interposition grafts through an anastomotic cuff technique in New Zealand white rabbits (3-4 kg; N = 80). RvD1 (1 μg) was delivered to the vein bypass grafts in a perivascular fashion, using either 25% Pluronic F127 gel (Sigma-Aldrich, St. Louis, Mo) or a thin bilayered poly(lactic-co-glycolic acid) (PLGA) film. No treatment (bypass only) and vehicle-loaded Pluronic gels or PLGA films served as controls. Delivery of RvD1 to venous tissue was evaluated 3 days later by liquid chromatography-tandem mass spectrometry. Total leukocyte infiltration, macrophage infiltration, and cell proliferation were evaluated by immunohistochemistry. Elastin and trichrome staining was performed on grafts harvested at 28 days after bypass to evaluate neointimal hyperplasia and vein graft remodeling.

RESULTS

Perivascular treatments did not influence rates of graft thrombosis (23%), major wound complications (4%), or death (3%). Leukocyte (CD45) and macrophage (RAM11) infiltration was significantly reduced in the RvD1 treatment groups vs controls at 3 days (60%-72% reduction; P < .01). Cellular proliferation (Ki67 index) was also significantly lower in RvD1-treated vs control grafts at 3 days (40%-50% reduction; P < .01). Treatment of vein grafts with RvD1-loaded gels reduced neointimal thickness at 28 days by 61% vs bypass only (P < .001) and by 63% vs vehicle gel (P < .001). RvD1-loaded PLGA films reduced neointimal formation at 28 days by 50% vs bypass only (P < .001). RvD1 treatment was also associated with reduced collagen deposition in vein grafts at 28 days.

CONCLUSIONS

Local perivascular delivery of RvD1 attenuates vein graft hyperplasia without associated toxicity in a rabbit carotid bypass model. This effect appears to be mediated by both reduced leukocyte recruitment and decreased cell proliferation within the graft. Perivascular PLGA films may also impart protection through biomechanical scaffolding in this venous arterialization model. Our studies provide further support for the potential therapeutic role of specialized proresolving lipid mediators such as D-series resolvins in modulating vascular injury and repair.

Genetic Polymorphisms Associated with the Neutrophil⁻Lymphocyte Ratio and Their Clinical Implications for Metabolic Risk Factors

Background: The neutrophil–lymphocyte ratio (NLR) is a valuable prognostic or predictive biomarker in various diseases, but the genetic factors that underlie the NLR have not been studied. We attempted to investigate polymorphisms related to NLR phenotype and analyze their ability to predict metabolic risks. Methods: A genome-wide association study was performed with log-transformed NLR using an Affymetrix Axiom™ KORV1.1-96 Array. Regression models for metabolic risk status were designed using the identified significant single-nucleotide polymorphisms (SNPs). Results: We identified four SNPs near the TMEM116, NAA25, and PTPN11 genes that were associated with the NLR. The top SNP associated with the log-transformed NLR was rs76181728 in TMEM116. A case–control study was performed to analyze the metabolic risks associated with each SNP after adjusting for age, sex, and body mass index (BMI). Three SNPs displayed significant odds ratios (ORs) for increased blood pressure and increased waist circumference. In the regression model for metabolic syndrome, rs76181728 showed a significant association (OR = 1.465, 95% confidence interval (CI) = 1.091–1.969, P = 0.011) after adjustment for the NLR phenotype. Conclusions: We identified four novel SNPs that are associated with the NLR in healthy Koreans. SNPs in relevant genes might therefore serve as biomarkers for metabolic risks.

Paradigm shift - Metabolic transformation of docosahexaenoic and eicosapentaenoic acids to bioactives exemplify the promise of fatty acid drug discovery

Fatty acid drug discovery (FADD) is defined as the identification of novel, specialized bioactive mediators that are derived from fatty acids and have precise pharmacological/therapeutic potential. A number of reports indicate that dietary intake of omega-3 fatty acids and limited intake of omega-6 promotes overall health benefits. In 1929, Burr and Burr indicated the significant role of essential fatty acids for survival and functional health of many organs. In reference to specific dietary benefits of differential omega-3 fatty acids, docosahexaenoic and eicosapentaenoic acids (DHA and EPA) are transformed to monohydroxy, dihydroxy, trihydroxy, and other complex mediators during infection, injury, and exercise to resolve inflammation. The presented FADD approach describes the metabolic transformation of DHA and EPA in response to injury, infection, and exercise to govern uncontrolled inflammation. Metabolic transformation of DHA and EPA into a number of pro-resolving molecules exemplifies a novel, inexpensive approach compared to traditional, expensive drug discovery. DHA and EPA have been recommended for prevention of cardiovascular disease since 1970. Therefore, the FADD approach is relevant to cardiovascular disease and resolution of inflammation in many injury models. Future research demands identification of novel action targets, receptors for biomolecules, mechanism(s), and drug-interactions with resolvins in order to maintain homeostasis.

PRN473, an inhibitor of Bruton's tyrosine kinase, inhibits neutrophil recruitment via inhibition of macrophage antigen-1 signalling

BACKGROUND AND PURPOSE

Following inflammatory stimuli, neutrophils are recruited to sites of inflammation and exert effector functions that often have deleterious effects on tissue integrity, which can lead to organ failure. Bruton's tyrosine kinase (Btk) is expressed in neutrophils and constitutes a promising pharmacological target for neutrophil-mediated tissue damage. Here, we evaluate a selective reversible inhibitor of Btk, PRN473, for its ability to dampen neutrophil influx via inhibition of adhesion receptor signalling pathways.

EXPERIMENTAL APPROACH

In vitro assays were used to assess fMLP receptor 1 (Fpr-1)-mediated binding of ligands to the adhesion receptors macrophage antigen-1 (Mac-1) and lymphocyte function antigen-1. Intravital microscopy of the murine cremaster was used to evaluate post-adhesion strengthening and endoluminal crawling. Finally, neutrophil influx was visualized in a clinically relevant model of sterile liver injury in vivo. Btk knockout animals were used as points of reference for Btk functions.

KEY RESULTS

Pharmacological inhibition of Btk by PRN473 reduced fMLP-induced phosphorylation of Btk and Mac-1 activation. Biochemical experiments demonstrated the specificity of the inhibitor. PRN473 (20 mg·kg^-1 ) significantly reduced intravascular crawling and neutrophil recruitment into inflamed tissue in a model of sterile liver injury, down to levels seen in Btk-deficient animals. A higher dose did not provide additional reduction of intravascular crawling and neutrophil recruitment.

CONCLUSIONS AND IMPLICATIONS

PRN473, a highly selective inhibitor of Btk, potently attenuates sterile liver injury by inhibiting the activation of the β₂ -integrin Mac-1 and subsequently neutrophil recruitment into inflamed tissue.

Transgenic Mice Expressing Human Proteinase 3 Exhibit Sustained Neutrophil-Associated Peritonitis

Proteinase 3 (PR3) is a myeloid serine protease expressed in neutrophils, monocytes, and macrophages. PR3 has a number of well-characterized proinflammatory functions, including cleaving and activating chemokines and controlling cell survival and proliferation. When presented on the surface of apoptotic neutrophils, PR3 can disrupt the normal anti-inflammatory reprogramming of macrophages following the phagocytosis of apoptotic cells. To better understand the function of PR3 in vivo, we generated a human PR3 transgenic mouse (hPR3Tg). During zymosan-induced peritonitis, hPR3Tg displayed an increased accumulation of neutrophils within the peritoneal cavity compared with wild-type control mice, with no difference in the recruitment of macrophages or B or T lymphocytes. Mice were also subjected to cecum ligation and puncture, a model used to induce peritoneal inflammation through infection. hPR3Tg displayed decreased survival rates in acute sepsis, associated with increased neutrophil extravasation. The decreased survival and increased neutrophil accumulation were associated with the cleavage of annexin A1, a powerful anti-inflammatory protein known to facilitate the resolution of inflammation. Additionally, neutrophils from hPR3Tg displayed enhanced survival during apoptosis compared with controls, and this may also contribute to the increased accumulation observed during the later stages of inflammation. Taken together, our data suggest that human PR3 plays a proinflammatory role during acute inflammatory responses by affecting neutrophil accumulation, survival, and the resolution of inflammation.

Actors and Factors in the Resolution of Intestinal Inflammation: Lipid Mediators As a New Approach to Therapy in Inflammatory Bowel Diseases

In the last few decades, the pathogenesis of inflammatory bowel disease (IBD) in genetically predisposed subjects susceptible to specific environmental factors has been attributed to disturbance of both the immune and non-immune system and/or to the imbalanced interactions with microbes. However, increasing evidences support the idea that defects in pro-resolving pathways might strongly contribute to IBD onset. The resolution of inflammation is now recognized as a dynamic event coordinated by specialized pro-resolving lipid mediators (LMs), which dampen inflammation-sustaining events, such as angiogenesis, release of pro-inflammatory cytokines, clearance of apoptotic cells, and microorganisms. Among these pro-resolving molecules, those derived from essential polyunsaturated fatty acids (PUFAs) have been shown to induce favorable effects on a plethora of human inflammatory disorders, including IBD. Here, we offer a summary of mechanisms involving both cellular and molecular components of the immune response and underlying the anti-inflammatory and pro-resolving properties of PUFAs and their derivatives in the gut, focusing on both ω-3 and ω-6 LMs. These fatty acids may influence IBD progression by: reducing neutrophil transmigration across the intestinal vasculature and the epithelium, preventing the release of pro-inflammatory cytokines and the up-regulation of adhesion molecules, and finally by promoting the production of other pro-resolving molecules. We also discuss the numerous attempts in using pro-resolving PUFAs to ameliorate intestinal inflammation, both in patients with IBD and mouse models. Although their effects in reducing inflammation is incontestable, results from previous works describing the effects of PUFA administration to prevent or treat IBD are controversial. Therefore, more efforts are needed not only to identify and explain the physiological functions of PUFAs in the gut, but also to unveil novel biosynthetic pathways of these pro-resolving LMs that may be dysregulated in these gut-related disorders. We suppose that either PUFAs or new medications specifically promoting resolution-regulating mediators and pathways will be much better tolerated by patients with IBD, with the advantage of avoiding immune suppression.

Neutrophil-to-lymphocyte ratio is associated with diabetic peripheral neuropathy in type 2 diabetes patients

OBJECTIVE

Diabetic peripheral neuropathy (DPN) had been demonstrated as a chronic inflammation state and one of the most common complications of type 2 diabetes mellitus (T2DM). Neutrophil-to-lymphocyte ratio (NLR) is a novel marker to reflect many kinds of chronic inflammation disease including diabetes. We aim to evaluate the association between NLR and DPN and to determine whether NLR could be a new indicator of DPN in type 2 diabetes patients.

METHODS

We retrospect the consecutive medical files of T2DM patients. Nerve conduction velocity (NCV), vibration perception threshold (VPT) and the data for complete blood count were recorded. Patients were divided into tertiles based on admission NLR values. Clinical parameters were firstly compared among groups. Then, logistic regression and ROC analysis were performed.

RESULTS

Percentages of DPN were 42.60%, 54.97% and 65.50%, in the low, middle and high tertile, respectively (n=72, 94 and 112, p<0.05). VPT values were 13.75±7.97, 15.01±9.60 and 16.78±10.92, respectively, (p<0.05). NCV in different nerves decreased with the increase of NLR (p<0.05). After adjusting potential related factors, NLR was still related to status of DPN in the logistic regression (r=1.743, p=0.001). Area under ROC was 0.619 (p<0.001).

CONCLUSION

The present study showed that T2DM patients with higher NLR levels might be more likely to develop peripheral neuropathy complication. NLR levels grow with the increase of NCV and VPT results. As a predictor of DPN, NLR could be used in clinical practice to help doctors understand the level of DPN progression.

Autophagy and inflammation

Autophagy is a homeostatic mechanism involved in the disposal of damaged organelles, denatured proteins as well as invaded pathogens through a lysosomal degradation pathway. Recently, increasing evidences have demonstrated its role in both innate and adaptive immunity, and thereby influence the pathogenesis of inflammatory diseases. The detection of autophagy machinery facilitated the measurement of autophagy during physiological and pathophysiological processes. Autophagy plays critical roles in inflammation through influencing the development, homeostasis and survival of inflammatory cells, including macrophages, neutrophils and lymphocytes; effecting the transcription, processing and secretion of a number of cytokines, as well as being regulated by cytokines. Recently, autophagy-dependent mechanisms have been studied in the pathogenesis of several inflammatory diseases, including infectious diseases, Crohn’s disease, cystic fibrosis, pulmonary hypertension, chronic obstructive pulmonary diseases and so on. These studies suggested that modulation of autophagy might lead to therapeutic interventions for diseases associated with inflammation. Here we highlight recent advances in investigating the roles of autophagy in inflammation as well as inflammatory diseases.

A Role for Neutrophils in Viral Respiratory Disease

Neutrophils are immune cells that are well known to be present during many types of lung diseases associated with acute respiratory distress syndrome (ARDS) and may contribute to acute lung injury. Neutrophils are poorly studied with respect to viral infection, and specifically to respiratory viral disease. Influenza A virus (IAV) infection is the cause of a respiratory disease that poses a significant global public health concern. Influenza disease presents as a relatively mild and self-limiting although highly pathogenic forms exist. Neutrophils increase in the respiratory tract during infection with mild seasonal IAV, moderate and severe epidemic IAV infection, and emerging highly pathogenic avian influenza (HPAI). During severe influenza pneumonia and HPAI infection, the number of neutrophils in the lower respiratory tract is correlated with disease severity. Thus, comparative analyses of the relationship between IAV infection and neutrophils provide insights into the relative contribution of host and viral factors that contribute to disease severity. Herein, we review the contribution of neutrophils to IAV disease pathogenesis and to other respiratory virus infections.

Resolution of inflammation in inflammatory bowel disease

Treatment of inflammatory bowel disease at present mainly targets mediators of inflammation to stop or suppress pro-inflammatory processes. Typical examples are steroids, suppression of T cells by thioguanine nucleotides, or antibodies against cytokines such as tumour necrosis factor, interleukin 12, or interleukin 23. In addition to suppression of inflammation, development of therapeutic strategies that support resolution of inflammation or that actively resolve inflammation might be desirable. Resolution of inflammation is now seen as an active process involving specific mediators (eg, lipid mediators or specific cytokines) that is mandatory to restore organ function and completely shut down inflammation. The molecular pathways involved in resolution of inflammation have been investigated in recent years and could be adopted in treatment strategies for inflammatory bowel disease. Among these approaches are anti-integrin strategies and means to produce or locally increase restitution or resolution factors, such as restoration of the activity of transforming growth factor-β by anti-SMAD7 antisense oligonucleotides. The potential role of inflammation-resolving lipid mediators (eg, resolvins), however, still warrants further study and clinical development. This Review focuses on the specific role of active resolution of inflammation in inflammatory bowel disease pathophysiology. Potential therapeutic targets based on these pathways are also discussed.

An overview of the role of neutrophils in innate immunity, inflammation and host-biomaterial integration

Despite considerable recent progress in defining neutrophil functions and behaviors in tissue repair, much remains to be determined with regards to its overall role in the tissue integration of biomaterials. This article provides an overview of the neutrophil’s numerous, important roles in both inflammation and resolution, and subsequently, their role in biomaterial integration. Neutrophils function in three primary capacities: generation of oxidative bursts, release of granules and formation of neutrophil extracellular traps (NETs); these combined functions enable neutrophil involvement in inflammation, macrophage recruitment, M2 macrophage differentiation, resolution of inflammation, angiogenesis, tumor formation and immune system activation. Neutrophils exhibit great flexibility to adjust to the prevalent microenvironmental conditions in the tissue; thus, the biomaterial composition and fabrication will potentially influence neutrophil behavior following confrontation. This review serves to highlight the neutrophil’s plasticity, reiterating that neutrophils are not just simple suicidal killers, but the true maestros of resolution and regeneration.

Neutrophil extracellular traps induce IL-1β production by macrophages in combination with lipopolysaccharide

Upon exposure to invading microorganisms, neutrophils undergo NETosis, a recently identified type of programmed cell death, and release neutrophil extracellular traps (NETs). NETs are described as an antimicrobial mechanism, based on the fact that NETs can trap microorganisms and exhibit bactericidal activity through the action of NET‑associated components. In contrast, the components of NETs have been recognized as damage‑associated molecular pattern molecules (DAMPs), which trigger inflammatory signals to induce cell death, inflammation and organ failure. In the present study, to clarify the effect of NETs on cytokine production by macrophages, mouse macrophage‑like J774 cells were treated with NETs in combination with lipopolysaccharide (LPS) as a constituent of pathogen‑associated molecular patterns. The results revealed that NETs significantly induced the production of interleukin (IL)‑1β by J774 cells in the presence of LPS. Notably, the NET/LPS‑induced IL‑1β production was inhibited by both caspase‑1 and caspase‑8 inhibitors. Furthermore, nucleases and serine protease inhibitors but not anti‑histone antibodies significantly inhibited the NET/LPS‑induced IL‑1β production. Moreover, we confirmed that caspase‑1 and caspase‑8 were activated by NETs/LPS, and the combination of LPS, DNA and neutrophil elastase induced IL‑1β production in reconstitution experiments. These observations indicate that NETs induce the production of IL‑1β by J774 macrophages in combination with LPS via the caspase‑1 and caspase‑8 pathways, and NET‑associated DNA and serine proteases are involved in NET/LPS‑induced IL‑1β production as essential components.

The Dual Role of Neutrophils in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis, are characterised by aberrant immunological responses leading to chronic inflammation without tissue regeneration. These two diseases are considered distinct entities, and there is some evidence that neutrophil behaviour, above all other aspects of immunity, clearly separate them. Neutrophils are the first immune cells recruited to the site of inflammation, and their action is crucial to limit invasion by microorganisms. Furthermore, they play an essential role in proper resolution of inflammation. When these processes are not tightly regulated, they can trigger positive feedback amplification loops that promote neutrophil activation, leading to significant tissue damage and evolution toward chronic disease. Defective chemotaxis, as observed in Crohn’s disease, can also contribute to the disease through impaired microbe elimination. In addition, through NET production, neutrophils may be involved in thrombo-embolic events frequently observed in IBD patients. While the role of neutrophils has been studied in different animal models of IBD for many years, their contribution to the pathogenesis of IBD remains poorly understood, and no molecules targeting neutrophils are used and validated for the treatment of these pathologies. Therefore, it is crucial to improve our understanding of their mode of action in these particular conditions in order to provide new therapeutic avenues for IBD.

A combination of the neutrophil-to-lymphocyte ratio and the GRACE risk score better predicts PCI outcomes in Chinese Han patients with acute coronary syndrome

Objective:

The aims of this study are to evaluate the relationship between the Global Registry of Acute Coronary Events (GRACE) risk score and neutrophil to lymphocyte ratio (NLR) and to determine whether a combination of these factors improves the predictive value for long-term cardiovascular events in Chinese Han patients with acute coronary syndrome (ACS).

Methods:

In this prospective, observational, and single-center study, NLRs (neutrophil count/lymphocyte count) were calculated from the complete blood count of 1050 patients with ACS, whereas GRACE risk scores were calculated from patients’ clinical parameters obtained on arrival at our hospital. Cox proportional hazards models were used to determine independent factors associated with cardiovascular events.

Results:

NLR was positively correlated with the GRACE risk score (r=0.66, p<0.001), and both the GRACE risk score (HR: 1.01; 95% CI: 1.01–1.02; p<0.001) and NLR (HR: 1.09; 95% CI: 1.06–1.14; p<0.001) independently predicted cardiovascular events. The area under the receiver operating characteristic (ROC) curve was 0.69 (95% CI: 0.64–0.72; p<0.001) when the GRACE score was calculated alone; however, it significantly increased (p<0.001) to 0.77 (95% CI: 0.74–0.80; p<0.001) when the GRACE score was combined with NLR.

Conclusion:

This study shows for the first time that NLR is positively associated with the GRACE risk score and demonstrates that a combination of these two factors may improve the predictive value for cardiovascular events in Chinese Han patients with ACS.

Ameliorative Effects of Curcumin on Fibrinogen-Like Protein-2 Gene Expression, Some Oxido-Inflammatory and Apoptotic Markers in a Rat Model of l-Arginine-Induced Acute Pancreatitis

The aim of the study was to investigate the ameliorative effects of curcumin on fibrinogen like protein-2 (fgl-2), some oxido-inflammatory and apoptotic markers in rat-induced acute pancreatitis (AP). Seventy-five albino rats were divided into control group, l-arginine (l-Arg)-induced AP group, curcumin pre-treated group before AP induction, curcumin post-treated group after AP induction, and curcumin injected group only. AP group showed severe necrotizing pancreatitis confirmed by histopathological changes and elevations in serum amylase and lipase activities, levels of epithelial neutrophil-activating peptide 78, tissue content of protein carbonyls, levels of tumor necrosis factor α, and caspase-3 as well as myeloperoxidase activity. Significant elevation in pancreatic fgl-2 mRNA expression was detected in AP group. Improvement of all parameters was detected with increase of caspase-3 in both curcumin-treated groups that confirmed curcumin ameliorative effects against AP through induction of apoptosis and inhibition of micro-thrombosis, inflammation, and oxidative stress.

Mangosenone F, A Furanoxanthone from Garciana mangostana, Induces Reactive Oxygen Species-Mediated Apoptosis in Lung Cancer Cells and Decreases Xenograft Tumor Growth

Mangosenone F (MSF), a natural xanthone, was isolated form Carcinia mangotana, and a few studies have reported its glycosidase inhibitor effect. In this study we investigated the anti lung cancer effect of MSF both in vitro and in vivo. MSF inhibited cancer cell cytotoxicity and induced and induced apoptosis via reactive oxygen species (ROS) generation in NCI-H460. MSF treatment also showed in pronounced release of apoptogenic cytochrome c from the mitochondria to the cytosol, downregulation of Bcl-2 and Bcl-xL, and upregulation of Bax, suggesting that caspase-mediated pathways were involved in MSF-induced apoptosis. ROS activation of the mitogen-activated protein kinase signaling pathway was shown to play a predominant role in the apoptosis mechanism of MSF. Compared with cisplatin treatment, MSF treatment showed significantly increased inhibition of the growth of NCI-H460 cells xenografted in nude mice. Together, these results indicate the potential of MSF as a candidate natural anticancer drug by promoting ROS production.

Lipopolysaccharide (LPS) exposure differently affects allergic asthma exacerbations and its amelioration by intranasal curcumin in mice

AIM

Lipopolysaccharide (LPS) is ubiquitous in the environment and can therefore, exacerbate allergic responses. Studies have suggested immunoregulatory effects of LPS according to route, dose and stage of exposure. Present study has examined whether dose and stage of LPS exposure (during sensitization and challenge with OVA) exacerbates airway inflammations, antigen specific-IgE level, histamine release, Th1/Th2 cytokine response. Further, anti-asthmatic potential of curcumin, through intranasal route has been evaluated for the first time in LPS induced airway inflammation in an ovalbumin (OVA)-challenged mouse asthma model.

METHODS

Balb/c mice were first sensitized with OVA on 1st and 8th day and exposed to two LPS doses (0.1/1.0 μg) separately on 2nd day and then further exposed to LPS with OVA-aerosol (from 9 to 14 day). Further, lower LPS dose (0.1 μg) was chosen for OVA exposed mouse model of asthma exacerbation study. Intranasal curcumin was administered from 9th to 14th day before every LPS exposure.

RESULTS

Exposure to LPS (0.1 μg) exacerbates airway inflammations in terms of IgE level, Th2-cytokine response (IL-4 and IL-5), histamine release, EPO and MPO activities and oxidative stress. Intranasal curcumin has effectively ameliorated airway exacerbations whereas dexamethasone, a known glucocorticosteroid, was not promising as compared to intranasal curcumin.

CONCLUSION

Schedule and dose of LPS exposure determines asthma exacerbations and intranasal curcumin could be better immunomodulatory agent in LPS exposed asthma exacerbations.