Inflammatory Resolution: new opportunities for drug discovery

Spatial considerations in the resolution of inflammation: Elucidating leukocyte interactions via an experimentally-calibrated agent-based model

Many common medical conditions (such as cancer, arthritis, chronic obstructive pulmonary disease (COPD), and others) are associated with inflammation, and even more so when combined with the effects of ageing and multimorbidity. While the inflammatory response varies in different tissue types, under disease and in response to therapeutic interventions, it has common interactions that occur between immune cells and inflammatory mediators. Understanding these underlying inflammatory mechanisms is key in progressing treatments and therapies for numerous inflammatory conditions. It is now considered that constituent mechanisms of the inflammatory response can be actively manipulated in order to drive resolution of inflammatory damage; particularly, those mechanisms related to the pro-inflammatory role of neutrophils and the anti-inflammatory role of macrophages. In this article, we describe the assembly of a hybrid mathematical model in which the spatial spread of inflammatory mediators is described through partial differential equations, and immune cells (neutrophils and macrophages) are described individually via an agent-based modelling approach. We pay close attention to how immune cells chemotax toward pro-inflammatory mediators, presenting a model for cell chemotaxis that is calibrated against experimentally observed cell trajectories in healthy and COPD-affected scenarios. We illustrate how variations in key model parameters can drive the switch from resolution of inflammation to chronic outcomes, and show that aberrant neutrophil chemotaxis can move an otherwise healthy outcome to one of chronicity. Finally, we reflect on our results in the context of the on-going hunt for new therapeutic interventions.

Inflammation is the body’s primary defence to harmful stimuli such as infections, toxins and tissue strain but also underlies a much broader range of conditions, including asthma, arthritis and cancer. The inflammatory response is key in resolving injury to facilitate recovery, and involves a range of interactions between immune cells (leukocytes, neutrophils and macrophages in particular) and inflammatory mediators. Immune cells are recruited from the blood stream in response to injury. Once in tissue, neutrophils release toxins to kill invading agents and resolve damage; however, if not carefully managed by other immune cells (mainly macrophages), their responses can increase inflammation instead of helping to resolve it. We model these interactions in response to damage using a spatial model, examining how a healthy response can prevent localised inflammation from spreading. We pay close attention to how cells migrate toward the damaged area, as many inflammatory conditions are associated with impairment of this process. We calibrate our model against experimentally-observed cell trajectories from healthy patients and patients with chronic obstructive pulmonary disease. We illustrate that a healthy outcome depends strongly upon efficient cell migration and a delicate balance between the pro- and anti-inflammatory effects of neutrophils and macrophages.

Prostaglandin A1 Decreases the Phosphorylation of Tau by Activating Protein Phosphatase 2A via a Michael Addition Mechanism at Cysteine 377

Prostaglandin (PG) A1 is a metabolic product of cyclooxygenase 2 (COX-2) that is potentially involved in regulating the development and progression of Alzheimer's disease (AD). PGA1 is a cyclopentenone (cy) PG characterized by the presence of a chemically reactive α,β-unsaturated carbonyl. PGA1 is potentially involved in the regulation of multiple biological processes via Michael addition; however, the specific roles of PGA1 in AD remain unclear. Tau^P301S transgenic (Tg) mice were used as in vivo AD models, and neuroblastoma (N) 2a cells were used as an in vitro neuronal model. The PGA1-binding proteins were identified by HPLC-MS-MS after intracerebroventricular injection (i.c.v) of PGA1. Western blotting was used to determine tau phosphorylation in PGA1-treated Tg mice in the absence or in the presence of okadaic acid (OA), an inhibitor of protein phosphatase (PP) 2A. A combination of pull-down assay, immunoprecipitation, western blotting, and HPLC-MS-MS was used to determine that the PP2A scaffold subunit A alpha (PPP2R1A) is activated by the direct binding of PGA1 to cysteine 377. The effect of inhibiting tau hyperphosphorylation was tested in the Morris maze to determine the inhibitory effects of PGA1 on cognitive decline in tau^P301S Tg mice. Incubation with N2a cells, pull-down assay, and mass spectrometry (MS) analysis revealed and indicated that PGA1 binds to more than 1000 proteins; some of these proteins are associated with AD and especially with tauopathies. Moreover, short-term administration of PGA1 in tau^P301S Tg mice significantly decreased tau phosphorylation at Thr181, Ser202, and Ser404 in a dose-dependent manner. This effect was caused by the activation of PPP2R1A in tau^P301S Tg mice. Importantly, PGA1 can form a Michael adduct with cysteine 377 of PPP2R1A, which is critical for the enzymatic activity of PP2A. Long-term treatment of tau^P301S Tg mice with PGA1 activated PP2A and significantly reduced tau phosphorylation resulting in improvements in cognitive decline in tau^P301S Tg mice. Our data provided new insight into the mechanisms of the ameliorating effects of PGA1 on cognitive decline in tau^P301S Tg mice by activating PP2A via a mechanism involving the formation of a Michael adduct with cysteine 377 of PPP2R1A.

Neutrophil heterogeneity and fate in inflamed tissues: implications for the resolution of inflammation

Neutrophils are polymorphonuclear leukocytes that play a central role in host defense against infection and tissue injury. They are rapidly recruited to the inflamed site and execute a variety of functions to clear invading pathogens and damaged cells. However, many of their defense mechanisms are capable of inflicting collateral tissue damage. Neutrophil-driven inflammation is a unifying mechanism underlying many common diseases. Efficient removal of neutrophils from inflammatory loci is critical for timely resolution of inflammation and return to homeostasis. Accumulating evidence challenges the classical view that neutrophils represent a homogeneous population and that halting neutrophil influx is sufficient to explain their rapid decline within inflamed loci during the resolution of protective inflammation. Hence, understanding the mechanisms that govern neutrophil functions and their removal from the inflammatory locus is critical for minimizing damage to the surrounding tissue and for return to homeostasis. In this review, we briefly address recent advances in characterizing neutrophil phenotypic and functional heterogeneity and the molecular mechanisms that determine the fate of neutrophils within inflammatory loci and the outcome of the inflammatory response. We also discuss how these mechanisms may be harnessed as potential therapeutic targets to facilitate resolution of inflammation.

Fatty Acid Mediators in the Tumor Microenvironment

Patients with cancer frequently overexpress inflammatory cytokines with an associated neutrophilia both of which may be downregulated by diets with high omega-3 polyunsaturated fatty acids (ω-3 PUFA). The anti-inflammatory activity of dietary ω-3 PUFA has been suggested to have anticancer properties and to improve survival of cancer patients. Currently, the majority of dietary research efforts do not differentiate between obesity and dietary fatty acid consumption as mediators of inflammatory cell expansion and tumor microenvironmental infiltration, initiation, and progression. In this chapter, we discuss the relationships between dietary lipids, inflammation, neoplasia and strategies to regulate these relationships. We posit that dietary composition, notably the ratio of ω-3 vs. ω-6 PUFA, regulates tumor initiation and progression and the frequency and sites of metastasis that, together, impact overall survival (OS). We focus on three broad topics: first, the role of dietary lipids in chronic inflammation and tumor initiation, progression, and regression; second, lipid mediators linking inflammation and cancer; and third, dietary lipid regulation of murine and human tumor initiation, progression, and metastasis.

Omega-3 derivatives, specialized pro-resolving mediators: Promising therapeutic tools for the treatment of pain in chronic liver disease

The main causes of liver injury are associated with inflammation and permanent damage. They can cause chronic liver disease (CLD), which is mainly related to viral hepatitis, alcohol consumption and non-alcoholic steatohepatitis, leading to fibrosis, cirrhosis and hepatocellular carcinoma. These conditions prevent the liver from working normally and make it begin to fail, which in turn may prompt a liver transplant. CLD and cirrhosis are the eleventh cause of death worldwide. At present, there are no approved pharmacological treatments to prevent, treat or resolve liver fibrosis. The prevalence of pain in the hepatic disease is elevated with ranges between 30% and 40%. Most of the pain drugs require hepatic function; therefore, the suitable control of pain is still a clinical challenge. Specialized pro-resolving mediators (SPM): lipoxins, resolvins, protectins and maresins, are potent endogenous molecules (nM concentrations) that modulate inflammatory body responses by reducing neutrophil infiltration, macrophage activity and pain sensitization. SPM have anti-inflammatory properties, stimulate tissue resolution, repair and regeneration, and exhibit anti-nociceptive actions. Furthermore, SPM were tried on different cellular, animal models and human observational data of liver injury, improving the pathogenesis of inflammation and fibrosis. In the present work, we will describe recent evidence that suggests that SPM can be used as a therapeutic option for CLD. Additionally, we will examine the role of SPM in the control of pain in pathologies associated with liver injury.

Tanshinone IIA alleviates brain damage in a mouse model of neuromyelitis optica spectrum disorder by inducing neutrophil apoptosis

Background

Neuromyelitis optica spectrum disorder (NMOSD), an autoimmune astrocytopathic disease associated with the anti-aquaporin-4 (AQP4) antibody, is characterized by extensive necrotic lesions primarily located on the optic nerves and spinal cord. Tanshinone IIA (TSA), an active natural compound extracted from Salvia miltiorrhiza Bunge, has profound immunosuppressive effects on neutrophils.

Objective

The present study aimed to evaluate the effect of TSA on NMOSD mice and explore the underlying mechanisms. Mice were initially administered TSA (pre-TSA group, n = 20) or vehicle (vehicle group, n = 20) every 8 h for 3 days, and then NMOSD model was induced by intracerebral injection of NMOSD-immunoglobulin G (NMO-IgG) and human complement (hC). In addition, post-TSA mice (n = 10) were administered equal dose of TSA at 8 h and 16 h after model induction. At 24 h after intracerebral injection, histological analysis was performed to assess the inhibitory effects of TSA on astrocyte damage, demyelination, and neuroinflammation in NMOSD mice, and western blotting was conducted to clarify the effect of TSA on the NF-κB and MAPK signaling pathways. Furthermore, flow cytometry and western blotting were conducted to verify the proapoptotic effects of TSA on neutrophils in vitro.

Results

There was a profound reduction in astrocyte damage and demyelination in the pre-TSA group and post-TSA group. However, prophylactic administration of TSA induced a better effect than therapeutic treatment. The number of infiltrated neutrophils was also decreased in the lesions of NMOSD mice that were pretreated with TSA. We confirmed that prophylactic administration of TSA significantly promoted neutrophil apoptosis in NMOSD lesions in vivo, and this proapoptotic effect was mediated by modulating the caspase pathway in the presence of inflammatory stimuli in vitro. In addition, TSA restricted activation of the NF-κB signaling pathway in vivo.

Conclusion

Our data provide evidence that TSA can act as a prophylactic agent that reduces NMO-IgG-induced damage in the mouse brain by enhancing the resolution of inflammation by inducing neutrophil apoptosis, and TSA may serve as a promising therapeutic agent for neutrophil-associated inflammatory disorders, such as NMOSD.

Immune response of human cultured cells towards macrocyclic Fe2PO and Fe2PC bioactive cyclophane complexes

Synthetic molecules that mimic the function of natural enzymes or molecules have untapped potential for use in the next generation of drugs. Cyclic compounds that contain aromatic rings are macrocyclic cyclophanes, and when they coordinate iron ions are of particular interest due to their antioxidant and biomimetic properties. However, little is known about the molecular responses at the cellular level. This study aims to evaluate the changes in immune gene expression in human cells exposed to the cyclophanes Fe₂PO and Fe₂PC. Confluent human embryonic kidney cells were exposed to either the cyclophane Fe₂PO or Fe₂PC before extraction of RNA. The expression of a panel of innate and adaptive immune genes was analyzed by quantitative real-time PCR. Evidence was found for an inflammatory response elicited by the cyclophane exposures. After 8 h of exposure, the cells increased the relative expression of inflammatory mediators such as interleukin 1; IRAK, which transduces signals between interleukin 1 receptors and the NFκB pathway; and the LPS pattern recognition receptor CD14. After 24 h of exposure, regulatory genes begin to counter the inflammation, as some genes involved in oxidative stress, apoptosis and non-inflammatory immune responses come into play. Both Fe₂PO and Fe₂PC induced similar immunogenetic changes in transcription profiles, but equal molar doses of Fe₂PC resulted in more robust responses. These data suggest that further work in whole animal models may provide more insights into the extent of systemic physiological changes induced by these cyclophanes.

Mechanisms and Points of Control in the Spread of Inflammation: A Mathematical Investigation

Understanding the mechanisms that control the body’s response to inflammation is of key importance, due to its involvement in myriad medical conditions, including cancer, arthritis, Alzheimer’s disease and asthma. While resolving inflammation has historically been considered a passive process, since the turn of the century the hunt for novel therapeutic interventions has begun to focus upon active manipulation of constituent mechanisms, particularly involving the roles of apoptosing neutrophils, phagocytosing macrophages and anti-inflammatory mediators. Moreover, there is growing interest in how inflammatory damage can spread spatially due to the motility of inflammatory mediators and immune cells. For example, impaired neutrophil chemotaxis is implicated in causing chronic inflammation under trauma and in ageing, while neutrophil migration is an attractive therapeutic target in ailments such as chronic obstructive pulmonary disease. We extend an existing homogeneous model that captures interactions between inflammatory mediators, neutrophils and macrophages to incorporate spatial behaviour. Through bifurcation analysis and numerical simulation, we show that spatially inhomogeneous outcomes can present close to the switch from bistability to guaranteed resolution in the corresponding homogeneous model. Finally, we show how aberrant spatial mechanisms can play a role in the failure of inflammation to resolve and discuss our results within the broader context of seeking novel inflammatory treatments.

15-Epi-LXA4 and 17-epi-RvD1 restore TLR9-mediated impaired neutrophil phagocytosis and accelerate resolution of lung inflammation

Timely resolution of bacterial infections critically depends on phagocytosis of invading pathogens by polymorphonuclear neutrophil granulocytes (PMNs), followed by PMN apoptosis and efferocytosis. Here we report that bacterial DNA (CpG DNA) and mitochondrial DNA impair phagocytosis and attenuate phagocytosis-induced apoptosis in human PMNs through Toll-like receptor 9 (TLR9)-mediated release of neutrophil elastase and proteinase 3 and subsequent down-regulation of the complement receptor C5aR. Consistently, CpG DNA delays pulmonary clearance of Escherichia coli in mice and suppresses PMN apoptosis, efferocytosis, and generation of proresolving lipid mediators, thereby prolonging lung inflammation evoked by E. coli Genetic deletion of TLR9 renders mice unresponsive to CpG DNA. We also show that aspirin-triggered 15-epi-lipoxin A₄ (15-epi-LXA₄) and 17-epi-resolvin D1 (17-epi-RvD1) through the receptor ALX/FPR2 antagonize cues from CpG DNA, preserve C5aR expression, restore impaired phagocytosis, and redirect human PMNs to apoptosis. Treatment of mice with 15-epi-LXA₄ or 17-epi-RvD1 at the peak of inflammation accelerates clearance of bacteria, blunts PMN accumulation, and promotes PMN apoptosis and efferocytosis, thereby facilitating resolution of E. coli-evoked lung injury. Collectively, these results uncover a TLR9-mediated endogenous mechanism that impairs PMN phagocytosis and prolongs inflammation, and demonstrate both endogenous and therapeutic potential for 15-epi-LXA₄ and 17-epi-RvD1 to restore impaired bacterial clearance and facilitate resolution of acute lung inflammation.

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.

Stereoselective synthesis of MaR2n-3 DPA

The first total synthesis of the n-3 docosapentaenoic derived oxygenated product MaR2n-3 DPA has been achieved. The 13R and 14S stereogenic centers were introduced using 2-deoxy-d-ribose in a chiral pool strategy. The geometry of the Z,E,E-triene moiety was prepared using highly E-selective Wittig- and Takai-olefination reactions as well as the Z-stereoselective Lindlar reduction. LC/MS-MS data of synthetic MaR2n-3 DPA matched data for the biosynthetic formed product that enabled the configurational assignment of this oxygenated natural product to be (7Z,9E,11E,13R,14S,16Z,19Z)-13,14-dihydroxydocosa-7,9,11,16,19-pentaenoic acid.

A novel hydrogel-based treatment for complete transection spinal cord injury repair is driven by microglia/macrophages repopulation

Microglia/macrophage mediated-inflammation, a main contributor to the microenvironment after spinal cord injury (SCI), persists for a long period of time and affects SCI repair. However, the effects of microglia/macrophage mediated-inflammation on neurogenic differentiation of endogenous neural stem/progenitor cells (NSPCs) are not well understood. In this study, to attenuate activated microglia/macrophage mediated-inflammation in the spinal cord of complete transection SCI mice, a combination of photo-crosslinked hydrogel transplantation and CSF1R inhibitor (PLX3397) treatment was used to replace the prolonged, activated microglia/macrophages via cell depletion and repopulation. This combined treatment in SCI mice produced a significant reduction in CD68-positive reactive microglia/macrophages and mRNA levels of pro-inflammatory factors, and a substantial increase in the number of Tuj1-positive neurons in the lesion area compared with single treatment methods. Moreover, most of the newborn Tuj1-positive neurons were confirmed to be generated from endogenous NSPCs using a genetic fate mapping mouse line (Nestin-CreERT2; LSL-tdTomato) that can label and trace NSPC marker-nestin expressing cells and their progenies. Collectively, our findings show that the combined treatment method for inhibiting microglia/macrophage mediated-inflammation promotes endogenous NSPC neurogenesis and improves functional recovery, which provides a promising therapeutic strategy for complete transection SCI.

Potential osteomyelitis biomarkers identified by plasma metabolome analysis in mice

Osteomyelitis, which often arises from a surgical-site infection, is a serious problem in orthopaedic surgery. However, there are no specific biomarkers for osteomyelitis. Here, to identify specific plasma biomarkers for osteomyelitis, we conducted metabolome analyses using a mouse osteomyelitis model and bioluminescence imaging. We divided adult male pathogen-free BALB/C mice into control, sham-control, and infected groups. In the infected group, a bioluminescent Staphylococcus aureus strain was inoculated into the femur, and osteomyelitis was detected by bioluminescence imaging. We next analysed the metabolome, by comprehensively measuring all of the small molecules. This analysis identified 279 metabolites, 12 of which were significantly higher and 45 were significantly lower in the infected group than in the sham-control and control groups. Principal component analysis identified sphingosine as the highest loading factor. Several acyl carnitines and fatty acids, particularly ω-3 and ω-6 polyunsaturated fatty acids, were significantly lower in the infected group. Several metabolites in the tricarboxylic acid cycle were lower in the infected group than in the other groups. Thus, we identified two sphingolipids, sphinganine and sphingosine, as positive biomarkers for mouse osteomyelitis, and two components in the tricarboxylic acid cycle, two-oxoglutarate and succinic acid, as negative biomarkers.

Cyclic AMP Regulates Key Features of Macrophages via PKA: Recruitment, Reprogramming and Efferocytosis

Macrophages are central to inflammation resolution, an active process aimed at restoring tissue homeostasis following an inflammatory response. Here, the effects of db-cAMP on macrophage phenotype and function were investigated. Injection of db-cAMP into the pleural cavity of mice induced monocytes recruitment in a manner dependent on PKA and CCR2/CCL2 pathways. Furthermore, db-cAMP promoted reprogramming of bone-marrow-derived macrophages to a M2 phenotype as seen by increased Arg-1/CD206/Ym-1 expression and IL-10 levels (M2 markers). Db-cAMP also showed a synergistic effect with IL-4 in inducing STAT-3 phosphorylation and Arg-1 expression. Importantly, db-cAMP prevented IFN-γ/LPS-induced macrophage polarization to M1-like as shown by increased Arg-1 associated to lower levels of M1 cytokines (TNF-α/IL-6) and p-STAT1. In vivo, db-cAMP reduced the number of M1 macrophages induced by LPS injection without changes in M2 and Mres numbers. Moreover, db-cAMP enhanced efferocytosis of apoptotic neutrophils in a PKA-dependent manner and increased the expression of Annexin A1 and CD36, two molecules associated with efferocytosis. Finally, inhibition of endogenous PKA during LPS-induced pleurisy impaired the physiological resolution of inflammation. Taken together, the results suggest that cAMP is involved in the major functions of macrophages, such as nonphlogistic recruitment, reprogramming and efferocytosis, all key processes for inflammation resolution.

Angelicae Gigantis Radix Regulates LPS-Induced Neuroinflammation in BV2 Microglia by Inhibiting NF-κB and MAPK Activity and Inducing Nrf-2 Activity

Angelicae Gigantis Radix (AGR) has been widely used as a traditional medicine in East Asia. The effects of AGR on neuroinflammation have not previously been studied in detail. In the study presented here, we investigated the antineuroinflammatory properties of this herb and its mechanism of operation. The effects of AGR on neuroinflammation were studied by measuring the production of inflammatory factors and related enzymes, and analyzing the expression levels of proteins and genes involved its activity, in lipopolysaccharide (LPS)-stimulated BV2 microglia. We found that AGR pretreatment strongly inhibits the production of nitric oxide (NO), cytokines, and the enzymes inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX)-2, and effectively induces the activation of heme oxygenase (HO)-1 and its regulator, nuclear factor erythroid 2-related factor 2 (Nrf-2). We also found that AGR effectively regulates the activation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK). We confirmed the antineuroinflammatory effects of the main constituents of the plant as identified by high-performance liquid chromatography (HPLC). Our results indicate that the neuroinflammation inhibitory activity of AGR occurs through inhibition of NF-κB and MAPK and activation of Nrf-2.

Transcriptional signature primes human oral mucosa for rapid wound healing

Oral mucosal wound healing has long been regarded as an ideal system of wound resolution. However, the intrinsic characteristics that mediate optimal healing at mucosal surfaces are poorly understood, particularly in humans. We present a unique comparative analysis between human oral and cutaneous wound healing using paired and sequential biopsies during the repair process. Using molecular profiling, we determined that wound-activated transcriptional networks are present at basal state in the oral mucosa, priming the epithelium for wound repair. We show that oral mucosal wound-related networks control epithelial cell differentiation and regulate inflammatory responses, highlighting fundamental global mechanisms of repair and inflammatory responses in humans. The paired comparative analysis allowed for the identification of differentially expressed SOX2 (sex-determining region Y-box 2) and PITX1 (paired-like homeodomain 1) transcriptional regulators in oral versus skin keratinocytes, conferring a unique identity to oral keratinocytes. We show that SOX2 and PITX1 transcriptional function has the potential to reprogram skin keratinocytes to increase cell migration and improve wound resolution in vivo. Our data provide insights into therapeutic targeting of chronic and nonhealing wounds based on greater understanding of the biology of healing in human mucosal and cutaneous environments.

Aspirin inhibits adipogenesis of tendon stem cells and lipids accumulation in rat injury tendon through regulating PTEN/PI3K/AKT signalling

Tendon injury repairs are big challenges in sports medicine, and fatty infiltration after tendon injury is very common and hampers tendon injury healing process. Tendon stem cells (TSCs), as precursors of tendon cells, have shown promising effect on injury tendon repair for their tenogenesis and tendon extracellular matrix formation. Adipocytes and lipids accumulation is a landmark event in pathological process of tendon injury, and this may induce tendon rupture in clinical practice. Based on this, it is important to inhibit TSCs adipogenesis and lipids infiltration to restore structure and function of injury tendon. Aspirin, as the representative of non‐steroidal anti‐inflammatory drugs (NSAIDs), has been widely used in tendon injury for its anti‐inflammatory and analgesic actions, but effect of aspirin on TSCs adipogenesis and fatty infiltration is still unclear. Under adipogenesis conditions, TSCs were treated with concentration gradient of aspirin. Oil red O staining was performed to observe changes of lipids accumulation. Next, we used RNA sequencing to compare profile changes of gene expression between induction group and aspirin‐treated group. Then, we verified the effect of filtrated signalling on TSCs adipogenesis. At last, we established rat tendon injury model and compared changes of biomechanical properties after aspirin treatment. The results showed that aspirin decreased lipids accumulation in injury tendon and inhibited TSCs adipogenesis. RNA sequencing filtrated PTEN/PI3K/AKT signalling as our target. After adding the signalling activators of VO‐Ohpic and IGF‐1, inhibited adipogenesis of TSCs was reversed. Still, aspirin promoted maximum loading, ultimate stress and breaking elongation of injury tendon. In conclusion, by down‐regulating PTEN/PI3K/AKT signalling, aspirin inhibited adipogenesis of TSCs and fatty infiltration in injury tendon, promoted biomechanical properties and decreased rupture risk of injury tendon. All these provided new therapeutic potential and medicine evidence of aspirin in treating tendon injury and tendinopathy.

Novel mediators and mechanisms in the resolution of infectious inflammation: evidence for vagus regulation

Excessive chronic inflammation is linked to many diseases and considered a stress factor in humans (Robbins Pathologic Basis of Disease. Philadelphia: W.B. Saunders Co., 1999, Proc Natl Acad Sci USA, 2008, 105: 17949, Immunity, 44, 2016, 44: 463, N Engl J Med, 2011, 364: 656). Today, the resolution of inflammation is widely recognized as a cellular biochemically active process involving biosynthesis of a novel superfamily of endogenous chemical signals coined specialized pro-resolving mediators (SPMs; Nature, 2014, 510:92). Herein, we review recent evidence, indicating a role for the vagus nerve and vagotomy in the regulation of lipid mediators. Vagotomy reduces pro-resolving mediators, including the lipoxins, resolvins, protectins and maresins, delaying resolution in mouse peritonitis. Vagotomy also delays resolution of Escherichia coli infection in mice. Specifically, right vagus regulates peritoneal Group 3 innate lymphoid cell (ILC-3) number and peritoneal macrophage responses with lipid mediator profile signatures with elevated pro-inflammatory eicosanoids and reduced resolvins, including the novel protective immunoresolvent agonist protectin conjugate in tissue regeneration1 (PCTR1). Acetylcholine upregulates PCTR biosynthesis, and administration of PCTR1 to vagotomized mice restores tissue resolution and host responses to E. coli infections. Results obtained with human vagus ex vivo indicate that vagus can produce both pro-inflammatory eicosanoids, such as prostaglandins and leukotrienes, as well as the SPM. Electrical stimulation of human vagus in vitro reduces both prostaglandins and leukotrienes and enhances resolvins and the other SPM. These results elucidate a host protective mechanism mediated by vagus stimulation of SPM that includes resolvins and PCTR1 to regulate myeloid antimicrobial functions and resolution of infection. Moreover, they define a new pro-resolution of inflammation reflex operative in mice and human tissue that involves a vagus SPM circuit.

Drug therapies and delivery mechanisms to treat perturbed skin wound healing

Acute wound healing is an orderly process of four overlapping events: haemostasis, inflammation, proliferation and remodelling. A drug delivery system with a temporal control of release could promote each of these events sequentially. However, acute wound healing normally proceeds very well in healthy individuals and there is little need to promote it. In the elderly and diabetics however, healing is often slow and wounds can become chronic and we need to promote their healing. Targeting the events of acute wound healing would not be appropriate for a chronic wound, which have stalled in the proinflammatory phase. They also have many additional problems such as poor circulation, low oxygen, high levels of leukocytes, high reactive oxygen species, high levels of proteolytic enzymes, high levels of proinflammatory cytokines, bacterial infection and high pH. The future challenge will be to tackle each of these negative factors to create a wound environment conducive to healing.

Resolvin E3 attenuates allergic airway inflammation via the interleukin-23-interleukin-17A pathway

We investigated the effects of resolvin E (RvE) 1, RvE2, and RvE3 on IL-4- and IL-33-stimulated bone marrow-derived dendritic cells (BMDCs) from house dust mite (HDM)-sensitized mice. We also investigated the role of RvE3 in a murine model of HDM-induced airway inflammation. In vitro, BMDCs from HDM-sensitized mice were stimulated with IL-4 and IL-33 and then treated with RvE1, RvE2, RvE3, or vehicle. RvE1, RvE2, and RvE3 suppressed IL-23 release from BMDCs. In vivo, RvE3 administrated to HDM-sensitized and challenged mice in the resolution phase promoted a decline in total numbers of inflammatory cells and eosinophils, reduced levels of IL-23 and IL-17 in lavage fluid, and suppressed IL-23 and IL-17A mRNA expression in lung and peribronchial lymph nodes. RvE3 also reduced resistance in the lungs of HDM-sensitized mice. A NanoBiT β-arrestin recruitment assay using human embryonic kidney 293 cells revealed that pretreatment with RvE3 suppressed the leukotriene B4 (LTB4)-induced β-arrestin 2 binding to LTB4 receptor 1 (BLT1R), indicating that RvE3 antagonistically interacts with BLT1R. Collectively, these findings indicate that RvE3 facilitates the resolution of allergic airway inflammation, partly by regulating BLT1R activity and selective cytokine release by dendritic cells. Our results accordingly identify RvE3 as a potential therapeutic target for the management of asthma.-Sato, M., Aoki-Saito, H., Fukuda, H., Ikeda, H., Koga, Y., Yatomi, M., Tsurumaki, H., Maeno, T., Saito, T., Nakakura, T., Mori, T., Yanagawa, M., Abe, M., Sako, Y., Dobashi, K., Ishizuka, T., Yamada, M., Shuto, S., Hisada, T. Resolvin E3 attenuates allergic airway inflammation via the interleukin-23-interleukin-17A pathway.

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.

Pathogenic stromal cells as therapeutic targets in joint inflammation

Knowledge of how the joint functions as an integrated unit in health and disease requires an understanding of the stromal cells populating the joint mesenchyme, including fibroblasts, tissue-resident macrophages and endothelial cells. Knowledge of the physiological and pathological mechanisms that involve joint mesenchymal stromal cells has begun to cast new light on why joint inflammation persists. The shared embryological origins of fibroblasts and endothelial cells might shape the behaviour of these cell types in diseased adult tissues. Cells of mesenchymal origin sustain inflammation in the synovial membrane and tendons by various mechanisms, and the important contribution of newly discovered fibroblast subtypes and their associated crosstalk with endothelial cells, tissue-resident macrophages and leukocytes is beginning to emerge. Knowledge of these mechanisms should help to shape the future therapeutic landscape and emphasizes the requirement for new strategies to address the pathogenic stroma and associated crosstalk between leukocytes and cells of mesenchymal origin.

Proresolving Mediators LXB4 and RvE1 Regulate Inflammation in Stromal Cells from Patients with Shoulder Tendon Tears

Tendon stromal cells isolated from patients with chronic shoulder rotator cuff tendon tears have dysregulated resolution responses. Current therapies do not address the biological processes concerned with persistent tendon inflammation; therefore, new therapeutic approaches that target tendon stromal cells are required. We examined whether two specialized proresolving mediators (SPMs), lipoxin B4 (LXB4) and resolvin E1 (RvE1), modulate the bioactive lipid mediator profiles of IL-1β–stimulated tendon cells derived from patients with shoulder tendon tears and healthy volunteers. We also examined whether LXB4 or RvE1 treatments moderated the proinflammatory phenotype of tendon tear stromal cells. Incubation of IL-1β–treated patient-derived tendon cells in LXB4 or RvE1 up-regulated concentrations of SPMs. RvE1 treatment of diseased tendon stromal cells increased 15-epi-LXB4 and regulated postaglandin F2α. LXB4 or RvE1 also induced expression of the SPM biosynthetic enzymes 12-lipoxygenase and 15-lipoxygenase. RvE1 treatment up-regulated the proresolving receptor human resolvin E1 compared with vehicle-treated cells. Incubation in LXB4 or RvE1 moderated the proinflammatory phenotype of patient-derived tendon tear cells, regulating markers of tendon inflammation, including podoplanin, CD90, phosphorylated signal transducer and activator of transcription 1, and IL-6. LXB4 and RvE1 counterregulate inflammatory processes in tendon stromal cells, supporting the role of these molecules as potential therapeutics to resolve tendon inflammation.

Regulation of Apoptotic Cell Clearance During Resolution of Inflammation

Programmed cell death (apoptosis) has an important role in the maintenance of tissue homeostasis as well as the progression and ultimate resolution of inflammation. During apoptosis, the cell undergoes morphological and biochemical changes [e.g., phosphatidylserine (PtdSer) exposure, caspase activation, changes in mitochondrial membrane potential and DNA cleavage] that act to shut down cellular function and mark the cell for phagocytic clearance. Tissue phagocytes bind and internalize apoptotic cells, bodies, and vesicles, providing a mechanism for the safe disposal of apoptotic material. Phagocytic removal of apoptotic cells before they undergo secondary necrosis reduces the potential for bystander damage to adjacent tissue and importantly initiates signaling pathways within the phagocytic cell that act to dampen inflammation. In a pathological context, excessive apoptosis or failure to clear apoptotic material results in secondary necrosis with the release of pro-inflammatory intracellular contents. In this review, we consider some of the mechanisms by which phagocytosis of apoptotic cells can be controlled. We suggest that matching apoptotic cell load with the capacity for apoptotic cell clearance within tissues may be important for therapeutic strategies that target the apoptotic process for treatment of inflammatory disease.

Activation of Resolution Pathways to Prevent and Fight Chronic Inflammation: Lessons From Asthma and Inflammatory Bowel Disease

Formerly considered as a passive process, the resolution of acute inflammation is now recognized as an active host response, with a cascade of coordinated cellular and molecular events that promotes termination of the inflammatory response and initiates tissue repair and healing. In a state of immune fitness, the resolution of inflammation is contained in time and space enabling the restoration of tissue homeostasis. There is increasing evidence that poor and/or inappropriate resolution of inflammation participates in the pathogenesis of chronic inflammatory diseases, extending in time the actions of pro-inflammatory mechanisms, and responsible in the long run for excessive tissue damage and pathology. In this review, we will focus on how resolution can be the target for therapy in "Th1/Th17 cell-driven" immune diseases and "Th2 cell-driven" immune diseases, with inflammatory bowel diseases (IBD) and asthma, as relevant examples. We describe the main cells and mediators stimulating the resolution of inflammation and discuss how pharmacological and dietary interventions but also life style factors, physical and psychological conditions, might influence the resolution phase. A better understanding of the impact of endogenous and exogenous factors on the resolution of inflammation might open a whole area in the development of personalized therapies in non-resolving chronic inflammatory diseases.

Local drug delivery systems in the management of periodontitis: A scientific review

Periodontitis (PD) is a microbial disease of tooth supporting tissues that results in progressive destruction of surrounding soft and hard tissues with eventual tooth mobility and exfoliation. Perioceutics, which includes the delivery of therapeutic agents via systemic and local means as an adjunct to mechanical therapy has revolutionized the arena of periodontal therapy. Selection of a right antimicrobial agent with appropriate route of drug administration is the key to successful periodontal therapy. Irrigating systems, fibers, gels, strips, films, microparticles, nanoparticles and low dose antimicrobial agents are some of the local drug delivery systems (LDDS) available in the field, which aims to deliver antimicrobial agents to sub-gingival diseased sites with minimal or no side-effects on other body sites. The present review aim to summarize the current state-of-the-art technology on LDDS in periodontal therapy ensuring the the practitioners are able to choose LDD agents which are custom made for a specific clinical condition.

In Silico Evaluation of Ibuprofen and Two Benzoylpropionic Acid Derivatives with Potential Anti-Inflammatory Activity

Inflammation is a complex reaction involving cellular and molecular components and an unspecific response to a specific aggression. The use of scientific and technological innovations as a research tool combining multidisciplinary knowledge in informatics, biotechnology, chemistry and biology are essential for optimizing time and reducing costs in the drug design. Thus, the integration of these in silico techniques makes it possible to search for new anti-inflammatory drugs with better pharmacokinetic and toxicological profiles compared to commercially used drugs. This in silico study evaluated the anti-inflammatory potential of two benzoylpropionic acid derivatives (MBPA and DHBPA) using molecular docking and their thermodynamic profiles by molecular dynamics, in addition to predicting oral bioavailability, bioactivity and toxicity. In accordance to our predictions the derivatives proposed here had the potential capacity for COX-2 inhibition in the human and mice enzyme, due to containing similar interactions with the control compound (ibuprofen). Ibuprofen showed toxic predictions of hepatotoxicity (in human, mouse and rat; toxicophoric group 2-arylacetic or 3-arylpropionic acid) and irritation of the gastrointestinal tract (in human, mouse and rat; toxicophoric group alpha-substituted propionic acid or ester) confirming the literature data, as well as the efficiency of the DEREK 10.0.2 program. Moreover, the proposed compounds are predicted to have a good oral bioavailability profile and low toxicity (LD50 < 700 mg/kg) and safety when compared to the commercial compound. Therefore, future studies are necessary to confirm the anti-inflammatory potential of these compounds.

Roles, Actions, and Therapeutic Potential of Specialized Pro-resolving Lipid Mediators for the Treatment of Inflammation in Cystic Fibrosis

Non-resolving inflammation is the main mechanism of morbidity and mortality among patients suffering from cystic fibrosis (CF), the most common life-threatening human genetic disease. Resolution of inflammation is an active process timely controlled by endogenous specialized pro-resolving lipid mediators (SPMs) produced locally in inflammatory loci to restrain this innate response, prevent further damages to the host, and permit return to homeostasis. Lipoxins, resolvins, protectins, and maresins are SPM derived from polyunsaturated fatty acids that limit excessive leukocyte infiltration and pro-inflammatory signals, stimulate innate microbial killing, and enhance resolution. Their unique chemical structures, receptors, and bioactions are being elucidated. Accruing data indicate that SPMs carry protective functions against unrelenting inflammation and infections in preclinical models and human CF systems. Here, we reviewed their roles and actions in controlling resolution of inflammation, evidence for their impairment in CF, and proofs of principle for their exploitation as innovative, non-immunosuppressive drugs to address inflammation and infections in CF.

15-Epi-LXA4 and MaR1 counter inflammation in stromal cells from patients with Achilles tendinopathy and rupture

Resolution of inflammation is poorly understood in Achilles tendon disorders. Herein, we investigated the bioactive lipid mediator profiles of tendon-derived stromal cells isolated from patients with Achilles tendinopathy (AT) or Achilles rupture (AR) under baseline and IL-1β–stimulated conditions. We also determined whether incubating these cells with 2 of the mediators produced by tendon-derived stromal cells, 15-epi-Lipoxin A₄ (15-epi-LXA₄) or maresin (MaR)-1, moderated their proinflammatory phenotype. Under baseline conditions, AT cells showed concurrent increased levels of proinflammatory eicosanoids and proresolving mediators compared with AR cells. IL-1β treatment induced profound prostaglandin E₂ release in AR compared with AT cells. Incubation of IL-1β treated AT and AR tendon-derived stromal cells in 15-epi-LXA₄ or MaR1 reduced proinflammatory eicosanoids and potentiated the release of proresolving mediators. These mediators also induced specialized proresolving mediator (SPM) biosynthetic enzymes arachidonate lipoxygenase (ALOX) 12 and ALOX15 and up-regulated the proresolving receptor ALX compared with vehicle-treated cells. Incubation in 15-epi-LXA₄ or MaR1 also moderated the proinflammatory phenotype of AT and AR cells, regulating podoplanin, CD90, signal transducer and activator of transcription (STAT)-1, IL-6, IFN regulatory factor (IRF) 5, and TLR4 and suppressed c-Jun N-terminal kinase 1/2/3, Lyn, STAT-3, and STAT-6 phosphokinase signaling. In summary, we identify proresolving mediators that are active in AT and AR and propose SPMs, including 15-epi-LXA₄ or MaR1, as a potential strategy to counterregulate inflammatory processes in these cells.—Dakin, S. G., Colas, R. A., Newton, J., Gwilym, S., Jones, N., Reid, H. A. B., Wood, S., Appleton, L., Wheway, K., Watkins, B., Dalli, J., Carr, A. J. 15-Epi-LXA₄ and MaR1 counter inflammation in stromal cells from patients with Achilles tendinopathy and rupture.

Divergent roles of prostacyclin and PGE2 in human tendinopathy

BACKGROUND

Tendon disease is a significant global healthcare burden whereby patients experience pain and disability; however, the mechanisms that underlie inflammation and pain are poorly understood. Herein, we investigated the role of prostaglandins as important mediators of inflammation and pain in tissues and cells derived from patients with tendinopathy.

METHODS

We studied supraspinatus and Achilles tendon biopsies from symptomatic patients with tendinopathy or rupture. Tendon-derived stromal cells (CD45negCD34neg) isolated from tendons were cultured and treated with interleukin-1β (IL-1β) to investigate prostaglandin production.

RESULTS

Diseased tendon tissues showed increased expression of prostacyclin receptor (IP) and enzymes catalyzing the biosynthesis of prostaglandins, including cyclooxygenase-1 (COX-1), COX-2, prostacyclin synthase (PGIS), and microsomal prostaglandin E synthase-1 (mPGES-1). PGIS co-localized with cells expressing Podoplanin, a marker of stromal fibroblast activation, and the nociceptive neuromodulator NMDAR-1. Treatment with IL-1β induced release of the prostacyclin metabolite 6-keto PGF1α in tendon cells isolated from diseased supraspinatus and Achilles tendons but not in cells from healthy comparator tendons. The same treatment induced profound prostaglandin E2 (PGE2) release in tendon cells derived from patients with supraspinatus tendon tears. Incubation of IL-1β treated diseased tendon cells with selective mPGES-1 inhibitor Compound III, reduced PGE2, and simultaneously increased 6-keto PGF1α production. Conversely, COX blockade with naproxen or NS-398 inhibited both PGE2 and 6-keto PGF1α production. Tendon biopsies from patients in whom symptoms had resolved showed increased PTGIS compared to biopsies from patients with persistent tendinopathy.

CONCLUSIONS

Our results suggest that PGE2 sustains inflammation and pain while prostacyclin may have a protective role in human tendon disease.

Effect of omega-3 fatty acid supplementation on resolvin (RvE1)-mediated suppression of inflammation in a mouse model of asthma

Objective: ResolvinE1 (RvE1), an endogenous lipid mediator derived from omega 3 fatty acids contributes to resolution of allergic inflammatory responses. We investigated effects of RvE1 (R) and omega 3 fatty acids (O) on airway reactivity and inflammation using allergic mice. Methods: Mice were divided into control (nonasthmatic; CON) and allergen sensitized-challenged (asthmatic; SEN) groups, and were sensitized i.p. on days 1, 6 with 0.2 μg ovalbumin (OVA) followed by 5% OVA aerosol challenges on days 11-13. RvE1 was administered i.p. postallergen challenge, while omega 3 fatty acids (fish oil) were administered via oral gavage once daily (days 1-13). Whole body plethysmography and bronchoalveolar lavage (BAL) studies were performed on day 14. Results: RvE1 attenuated airway responsiveness to methacholine (48 mg/ml) in treated asthmatic mice vs. nontreated (150 ± 27.88% in SEN vs. 54 ± 7.52% in SEN + R, p < .05). No difference was observed with omega-3 supplementation (115 ± 19.28% in SEN + O) or treatment with both RvE1 and omega 3 fatty acids (39 ± 12.37% in SEN + R + O vs. 54 ± 7.52% in SEN + R). Differential BAL cell analysis showed that RvE1 decreased eosinophils and neutrophils in SEN mice (p < .005) while no difference was observed with omega-3 fatty acids. SEN + R + O group had similar results as RvE1 treated mice, suggesting that only RvE1 attenuated inflammation. Conclusions: RvE1 attenuated airway responsiveness and inflammation in asthmatic mice. Omega-3 fatty acids, although a precursor for RvE1 formation, had no additive effects on RvE1 decreases in airway inflammation and airway reactivity. Our data suggests that omega-3 supplementation has little effect on airway inflammation and reactivity in our model of asthma.

In Vitro and In Vivo Anti-Inflammatory Effects of Polyphyllin VII through Downregulating MAPK and NF-κB Pathways

Background: Polyphyllin VII (PP7), a steroidal saponin from Paris polyphylla, has been found to exert strong anticancer activity. Little is known about the anti-inflammatory property of PP7. In this study, the anti-inflammatory activity and its underlying mechanisms of PP7 were evaluated in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and in multiple animal models. Methods: The content of nitric oxide (NO) was determined by spectrophotometry. The levels of prostaglandin E2 (PGE₂) and cytokines were measured by enzyme-linked immunosorbent assay (ELISA) assay. The mRNA expression of pro-inflammatory genes was determined by qPCR. The total and phosphorylated protein levels were examined by Western blotting. The in vivo anti-inflammatory activities were evaluated by using mouse and zebrafish models. Results: PP7 reduced the production of NO and PGE₂ and the protein and mRNA expressions of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and enzymes (inducible NO synthase [iNOS], cyclooxygenase-2 [COX-2], and Matrix metalloproteinase-9 [MMP-9]) in LPS-induced RAW264.7 cells by suppressing the NF-κB and MAPKs pathways. Notably, PP7 markedly inhibited xylene-induced ear edema and cotton pellet-induced granuloma formation in mice and suppressed LPS and CuSO₄-induced inflammation and toxicity in zebrafish embryos. Conclusion: This study demonstrates that PP7 exerts strong anti-inflammatory activities in multiple in vitro and in vivo models and suggests that PP7 is a potential novel therapeutic agent for inflammatory diseases.

Neutrophil Membrane-Derived Nanovesicles Alleviate Inflammation To Protect Mouse Brain Injury from Ischemic Stroke

Ischemic stroke is an acute and severe neurological disease, resulting in disability and death. Reperfusion to an ischemic brain is a means to reverse brain damage after stroke; however, this causes secondary tissue damage induced by inflammation responses, called ischemia/reperfusion (I/R) injury. Adhesion of neutrophils to endothelial cells underlies the initiation of inflammation in I/R. Inspired by this interaction, we report a drug delivery system comprised of neutrophil membrane-derived nanovesicles loaded with Resolvin D2 (RvD2) that can enhance resolution of inflammation, thus protecting brain damage during ischemic stroke. In the study, the middle cerebral artery occlusion (MCAO) mouse model was developed to mimic ischemic stroke. Using intravital microscopy of a live mouse brain, we visualized the binding of nanovesicles to inflamed brain vasculature for delivery of therapeutics to ischemic stroke lesions in real-time. We also observed that RvD2-loaded nanovesicles dramatically decreased inflammation in ischemic stroke and improved mouse neurological functions. Our study provides a strategy to inhibit neuroinflammation using neutrophil-derived nanovesicles for ischemic stroke therapy.

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 Protectin Family of Specialized Pro-resolving Mediators: Potent Immunoresolvents Enabling Innovative Approaches to Target Obesity and Diabetes

A western type diet and lifestyle play an important role in the development of chronic diseases, yet little insight into the precise cellular and biomolecular mechanisms has emerged. It is known that an unbalanced diet may result in obesity and diabetes. Sufficient amounts and proper balance of omega-6 and omega-3 polyunsaturated fatty acids is key for maintenance of health. The resolution of inflammation is now held to be a biosynthetically actively driven process precisely regulated and controlled by a superfamily of specialized pro-resolving mediators. Specialized pro-resolving mediators are biosynthesized from both omega-6 and omega-3 polyunsaturated fatty acids and are resolution agonists acting on distinct G-coupled protein receptors. These mediators display potent anti-inflammatory and pro-resolving bioactions with EC₅₀-values in the low nanomolar to picomolar range. The protectin (PD) family of specialized pro-resolving mediators is biosynthesized from the two omega-3 polyunsaturated fatty acids docosahexaenoic acid (DHA) and n–3 docosapentaenoic acid (n–3 DPA). All of the PDs display interesting bioactions as anti-inflammatory and pro-resolving agents. This review covers the bioactions, G-coupled protein receptors pharmacology, biosynthesis, and medicinal chemistry of the PD family of specialized pro-resolving mediators with an emphasis on obesity and anti-diabetic effects. In order to enable drug development and medicinal chemistry efforts against these diseases, stereoselective total organic synthesis of each of these mediators is required for confirmation of structure, stereochemical biosynthesis, and their functions. We provide an overview of our ongoing efforts and the current knowledge.

Immune regulation and anti-cancer activity by lipid inflammatory mediators

Rodent and clinical studies have documented that myeloid cell infiltration of tumors is associated with poor outcomes, neutrophilia and lymphocytopenia. This contrasts with increased lymphocyte infiltration of tumors, which is correlated with improved outcomes. Lifestyle parameters, such as obesity and diets with high levels of saturated fat and/or omega (ω)-6 polyunsaturated fatty acids (PUFAs), can influence these inflammatory parameters, including an increase in extramedullary myelopoiesis (EMM). While tumor secretion of growth factors (GFs) and chemokines regulate tumor-immune-cell crosstalk, lifestyle choices also contribute to inflammation, abnormal pathology and leukocyte infiltration of tumors. A relationship between obesity and high-fat diets (notably saturated fats in Western diets) and inflammation, tumor incidence, metastasis and poor outcomes is generally accepted. However, the mechanisms of dietary promotion of an inflammatory microenvironment and targeted drugs to inhibit the clinical sequelae are poorly understood. Thus, modifications of obesity and dietary fat may provide preventative or therapeutic approaches to control tumor-associated inflammation and disease progression. Currently, the majority of basic and clinical research does not differentiate between obesity and fatty acid consumption as mediators of inflammatory and neoplastic processes. In this review, we discuss the relationships between dietary PUFAs, inflammation and neoplasia and experimental strategies to improve our understanding of these relationships. We conclude that dietary composition, notably the ratio of ω-3 vs ω-6 PUFA regulates tumor growth and the frequency and sites of metastasis that together, impact overall survival (OS) in mice.

Role of Toll-like receptor 4/oxidant-coupled activation in regulating the biosynthesis of omega-3 polyunsaturated fatty acid derivative resolvin D1 in primary murine peritoneal macrophage

We have previously shown that reactive oxygen species (ROS) as prooxidants can activate Toll-like receptor 4 (TLR4) with the potential to initiate, propagate and maintain "sterile" inflammation of innate immunity, which plays a mediatory role in a host of human disease states. We now present new evidence that ROS can also activate TLR4 to counter the inflammatory phenotype by increasing the production of resolvin D1 (RvD1), which is a specialized anti-inflammatory and pro-resolving lipid mediator. We used primary murine peritoneal macrophages (pM) derived from both TLR4-WT and TLR4-KO mice as a cellular model. We used potassium peroxychromate (PPC) as a direct in vitro source of exogenous ROS. PPC treatment increased intracellular ROS levels, which decreased intracellular total antioxidant capacity, thus suggesting an enhanced cellular oxidative stress. PPC and LPS-EK (a TLR4-specific agonist) increased pro-inflammatory TNFα production with noeffect on IL-10, an anti-inflammatory cytokine. Treatment with the prooxidant increased the expression of 12 lipoxygenase (12-LOX) and 5-lipoxygenase (5-LOX) only in pM derived from TLR4 WT but not in pM from TLR4-KO mice. 5-LOX and 12-LOX are the key enzymes in the RvD1 biosynthetic pathway. In addition, PPC increased the expression of RvD1 receptor, a member of G-protein-coupled receptor only in pM from TLR4-WT mice. Our data support the involvement of TLR4-mediated oxidant-induced pro-inflammatory phenotypes that are in opposition to the production of anti-inflammatory/pro-resolution phenotypes in macrophages. Now, we show that through TLR4 activation, exogenous oxidants can play a role both in producing proinflammatory phenotypes at the same time that it enhances resolution of inflammation to maintain a state of cellular homeostasis and prevent tissue damage/disease.

Antipleuritic and Vascular Permeability Inhibition of the Ethyl Acetate-Petroleum Ether Stem Bark Extract of Maerua angolensis DC (Capparaceae) in Murine

Maerua angolensis has been used traditionally in the management of pain, arthritis, and rheumatism in Ghana and Nigeria but no scientific evidence is currently available to give credence to its folkloric use. The aim of this study was therefore to evaluate the anti-inflammatory effects of a stem bark extract of Maerua angolensis DC (MAE) in acute inflammatory models. The effects of MAE (30-300 mg kg⁻¹) on neutrophil infiltration, exudate volume, and endogenous antioxidant enzymes in lung tissues and lung morphology were evaluated with the carrageenan induced pleurisy model in Sprague Dawley rats. The effects of MAE (30-300 mg kg⁻¹) on vascular permeability were also evaluated in the acetic acid induced vascular permeability in ICR mice. MAE significantly reduced neutrophil infiltration, exudate volume, and lung tissue damage in carrageenan induced pleurisy. MAE increased the activities of antioxidant enzymes glutathione, superoxide dismutase, and catalase in lung tissues. The extract was also able to reduce myeloperoxidase activity and lipid peroxidation in lung tissues in carrageenan induced rat pleurisy. Vascular permeability was also attenuated by the extract with marked reduction of Evans blue dye leakage in acetic acid induced permeability assay. The results indicated that Maerua angolensis is effective in ameliorating inflammation induced by carrageenan and acetic acid. It also has the potential of increasing the activity of endogenous antioxidant enzymes.

Targeting formyl peptide receptors to facilitate the resolution of inflammation

The formyl peptide receptors (FPRs) are G protein coupled receptors that recognize a broad range of structurally distinct pathogen and danger-associated molecular patterns and mediate host defense to infection and tissue injury. It became evident that the cellular distribution and biological functions of FPRs extend beyond myeloid cells and governing their activation and trafficking. In recent years, significant progress has been made to position FPRs at check points that control the resolution of inflammation, tissue repair and return to homeostasis. Accumulating data indicate a role for FPRs in an ever-increasing range of human diseases, including atherosclerosis, chronic obstructive pulmonary disease, asthma, autoimmune diseases and cancer, in which dysregulated or defective resolution are increasingly recognized as critical component of the pathogenesis. This review summarizes recent advances on how FPRs recognize distinct ligands and integrate opposing cues to govern various responses and will discuss how this knowledge could be harnessed for developing novel therapeutic strategies to counter inflammation that underlies many human diseases.

Extract of Fructus Schisandrae chinensis Inhibits Neuroinflammation Mediator Production from Microglia via NF-κ B and MAPK Pathways

OBJECTIVE

To investigate the anti-neuroinflammation effect of extract of Fructus Schisandrae chinensis (EFSC) on lipopolysaccharide (LPS)-induced BV-2 cells and the possible involved mechanisms.

METHODS

Primary cortical neurons were isolated from embryonic (E17-18) cortices of Institute of Cancer Research (ICR) mouse fetuses. Primary microglia and astroglia were isolated from the frontal cortices of newborn ICR mouse. Different cells were cultured in specific culture medium. Cells were divided into 5 groups: control group, LPS group (treated with 1 μg/mL LPS only) and EFSC groups (treated with 1 μg/mL LPS and 100, 200 or 400 mg/mL EFSC, respectively). The effect of EFSC on cells viability was tested by methylthiazolyldiphenyltetrazolium bromide (MTT) colorimetric assay. EFSC-mediated inhibition of LPS-induced production of pro-inflammatory mediators, such as nitrite oxide (NO) and interleukin-6 (IL-6) were quantified and neuron-protection effect against microglia-mediated inflammation injury was tested by hoechst 33258 apoptosis assay and crystal violet staining assay. The expression of pro-inflammatory marker proteins was evaluated by Western blot analysis or immunofluorescence.

RESULTS

EFSC (200 and 400 mg/mL) reduced NO, IL-6, inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) expression in LPS-induced BV-2 cells (P<0.01 or P<0.05). EFSC (200 and 400 mg/mL) reduced the expression of NO in LPS-induced primary microglia and astroglia (P<0.01). In addition, EFSC alleviated cell apoptosis and inflammation injury in neurons exposed to microglia-conditioned medium (P<0.01). The mechanistic studies indicated EFSC could suppress nuclear factor (NF)-?B phosphorylation and its nuclear translocation (P<0.01). The anti-inflammatory effect of EFSC occurred through suppressed activation of mitogen-activated protein kinase (MAPK) pathway (P<0.01 or P<0.05).

CONCLUSION

EFSC acted as an anti-inflammatory agent in LPS-induced glia cells. These effects might be realized through blocking of NF-κB activity and inhibition of MAPK signaling pathways.

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.

Synergism in aluminum and mercury neurotoxicity

Aluminum and mercury are common neurotoxic contaminants in our environment - from the air we breathe to the water that we drink to the foods that we eat. It is remarkable that to date neither of these two well-established environmental neurotoxins (i.e. those having a general toxicity towards brain cells) and genotoxins (those agents which exhibit directed toxicity toward the genetic apparatus) have been critically studied, nor have their neurotoxicities been evaluated in human neurobiology or in cells of the human central nervous system (CNS). In this paper we report the effects of added aluminum [sulfate; Al₂(SO₄)₃] and/or mercury [sulfate; HgSO4] to human neuronal-glial (HNG) cells in primary co-culture using the evolution of the pro-inflammatory transcription factor NF-kB (p50/p65) complex as a critical indicator for the onset of inflammatory neurodegeneration and pathogenic inflammatory signaling. As indexed by significant induction of the NF-kB (p50/p65) complex the results indicate: (i) a notable increase in pro-inflammatory signaling imparted by each of these two environmental neurotoxins toward HNG cells in the ambient 20-200 nM range; and (ii) a significant synergism in the neurotoxicity when aluminum (sulfate) and mercury (sulfate) were added together. This is the first report on the neurotoxic effects of aluminum sulfate and/or mercury sulfate on the initiation of inflammatory signaling in human brain cells in primary culture. The effects aluminum+mercury together on other neurologically important signaling molecules or the effects of other combinations of common environmental metallic neurotoxins to human neurobiology currently remain not well understood but certainly warrant additional investigation and further study in laboratory animals, in human primary tissue cultures of CNS cells, and in other neurobiologically realistic experimental test systems.

Selective Modulation of TNF-TNFRs Signaling: Insights for Multiple Sclerosis Treatment

Autoimmunity develops when self-tolerance mechanisms are failing to protect healthy tissue. A sustained reaction to self is generated, which includes the generation of effector cells and molecules that destroy tissues. A way to restore this intrinsic tolerance is through immune modulation that aims at refurbishing this immunologically naïve or unresponsive state, thereby decreasing the aberrant immune reaction taking place. One major cytokine has been shown to play a pivotal role in several autoimmune diseases such as rheumatoid arthritis (RA) and multiple sclerosis (MS): tumor necrosis factor alpha (TNFα) modulates the induction and maintenance of an inflammatory process and it comes in two variants, soluble TNF (solTNF) and transmembrane bound TNF (tmTNF). tmTNF signals via TNFR1 and TNFR2, whereas solTNF signals mainly via TNFR1. TNFR1 is widely expressed and promotes mainly inflammation and apoptosis. Conversely, TNFR2 is restricted mainly to immune and endothelial cells and it is known to activate the pro-survival PI3K-Akt/PKB signaling pathway and to sustain regulatory T cells function. Anti-TNFα therapies are successfully used to treat diseases such as RA, colitis, and psoriasis. However, clinical studies with a non-selective inhibitor of TNFα in MS patients had to be halted due to exacerbation of clinical symptoms. One possible explanation for this failure is the non-selectivity of the treatment, which avoids TNFR2 stimulation and its immune and tissue protective properties. Thus, a receptor-selective modulation of TNFα signal pathways provides a novel therapeutic concept that might lead to new insights in MS pathology with major implications for its effective treatment.

Anti-Inflammatory Benefits of Antibiotics: Tylvalosin Induces Apoptosis of Porcine Neutrophils and Macrophages, Promotes Efferocytosis, and Inhibits Pro-Inflammatory CXCL-8, IL1α, and LTB4 Production, While Inducing the Release of Pro-Resolving Lipoxin A4 and Resolvin D1

Excessive accumulation of neutrophils and their uncontrolled death by necrosis at the site of inflammation exacerbates inflammatory responses and leads to self-amplifying tissue injury and loss of organ function, as exemplified in a variety of respiratory diseases. In homeostasis, neutrophils are inactivated by apoptosis, and non phlogistically removed by neighboring macrophages in a process known as efferocytosis, which promotes the resolution of inflammation. The present study assessed the potential anti-inflammatory and pro-resolution benefits of tylvalosin, a recently developed broad-spectrum veterinary macrolide derived from tylosin. Recent findings indicate that tylvalosin may modulate inflammation by suppressing NF-κB activation. Neutrophils and monocyte-derived macrophages were isolated from fresh blood samples obtained from 12- to 22-week-old pigs. Leukocytes exposed to vehicle or to tylvalosin (0.1, 1.0, or 10 µg/mL; 0.096-9.6 µM) were assessed at various time points for apoptosis, necrosis, efferocytosis, and changes in the production of cytokines and lipid mediators. The findings indicate that tylvalosin increases porcine neutrophil and macrophage apoptosis in a concentration- and time-dependent manner, without altering levels of necrosis or reactive oxygen species production. Importantly, tylvalosin increased the release of pro-resolving Lipoxin A₄ (LXA₄) and Resolvin D1 (RvD ₁ ) while inhibiting the production of pro-inflammatory Leukotriene B4 (LTB₄) in Ca²⁺ ionophore-stimulated porcine neutrophils. Tylvalosin increased neutrophil phospholipase C activity, an enzyme involved in releasing arachidonic acid from membrane stores. Tylvalosin also inhibited pro-inflammatory chemokine (C-X-C motif) ligand 8 (CXCL-8, also known as Interleukin-8) and interleukin-1 alpha (IL-1α) protein secretion in bacterial lipopolysaccharide-stimulated macrophages. Together, these data illustrate that tylvalosin has potent immunomodulatory effects in porcine leukocytes in addition to its antimicrobial properties.