The cAMP Pathway as Therapeutic Target in Autoimmune and Inflammatory Diseases

Molecular Targets and Biological Functions of cAMP Signaling in Arabidopsis

Cyclic AMP (cAMP) is a pivotal signaling molecule existing in almost all living organisms. However, the mechanism of cAMP signaling in plants remains very poorly understood. Here, we employ the engineered activity of soluble adenylate cyclase to induce cellular cAMP elevation in Arabidopsis thaliana plants and identify 427 cAMP-responsive genes (CRGs) through RNA-seq analysis. Induction of cellular cAMP elevation inhibits seed germination, disturbs phytohormone contents, promotes leaf senescence, impairs ethylene response, and compromises salt stress tolerance and pathogen resistance. A set of 62 transcription factors are among the CRGs, supporting a prominent role of cAMP in transcriptional regulation. The CRGs are significantly overrepresented in the pathways of plant hormone signal transduction, MAPK signaling, and diterpenoid biosynthesis, but they are also implicated in lipid, sugar, K⁺, nitrate signaling, and beyond. Our results provide a basic framework of cAMP signaling for the community to explore. The regulatory roles of cAMP signaling in plant plasticity are discussed.

Biochanin A Regulates Key Steps of Inflammation Resolution in a Model of Antigen-Induced Arthritis via GPR30/PKA-Dependent Mechanism

Biochanin A (BCA) is a natural organic compound of the class of phytochemicals known as flavonoids and isoflavone subclass predominantly found in red clover (Trifolium pratense). It has anti-inflammatory activity and some pro-resolving actions, such as neutrophil apoptosis. However, the effect of BCA in the resolution of inflammation is still poorly understood. In this study, we investigated the effects of BCA on the neutrophilic inflammatory response and its resolution in a model of antigen-induced arthritis. Male wild-type BALB/c mice were treated with BCA at the peak of the inflammatory process (12 h). BCA decreased the accumulation of migrated neutrophils, and this effect was associated with reduction of myeloperoxidase activity, IL-1β and CXCL1 levels, and the histological score in periarticular tissues. Joint dysfunction, as seen by mechanical hypernociception, was improved by treatment with BCA. The resolution interval (Ri) was also quantified, defining profiles of acute inflammatory parameters that include the amplitude and duration of the inflammatory response monitored by the neutrophil infiltration. BCA treatment shortened Ri from ∼23 h observed in vehicle-treated mice to ∼5.5 h, associated with an increase in apoptotic events and efferocytosis, both key steps for the resolution of inflammation. These effects of BCA were prevented by H89, an inhibitor of protein kinase A (PKA) and G15, a selective G protein–coupled receptor 30 (GPR30) antagonist. In line with the in vivo data, BCA also increased the efferocytic ability of murine bone marrow–derived macrophages. Collectively, these data indicate for the first time that BCA resolves neutrophilic inflammation acting in key steps of the resolution of inflammation, requiring activation of GPR30 and via stimulation of cAMP-dependent signaling.

Roflumilast as a Potential Therapeutic Agent for Cecal Ligation and Puncture-Induced Septic Lung Injury

PURPOSE/AIMS

This study focused on delineating the possible effects of roflumilast (ROF), a selective phosphodiesterase 4 (PDE4) inhibitor, in rats with cecal ligation and puncture (CLP)-induced polymicrobial sepsis, and investigated whether ROF can act as a protective agent in sepsis-induced lung damage.

MATERIAL AND METHODS

Four experimental groups were organized, each comprising eight rats: Control, Sepsis, Sepsis + ROF 0.5 mgkg^-1, and Sepsis + ROF 1 mgkg^-1 groups. A polymicrobial sepsis model was induced in the rats by cecal ligation and puncture under anesthesia. Twelve hours after sepsis induction, the lungs were obtained for biochemical, molecular, and histopathological analyses.

RESULTS

In the sepsis group's lungs, the TNF-α, IL-1β, and IL-6 mRNA expression levels peaked in the sepsis group's lung tissues, and ROF significantly decreased these levels compared with the sepsis group dose-dependently. ROF also significantly decreased MDA levels in septic lungs and increased antioxidant parameters (SOD and GSH) compared with the sepsis group. Histopathological analysis results supported biochemical and molecular results.

CONCLUSIONS

ROF, a PDE4 inhibitor, suppressed the expression levels of pro-inflammatory cytokines, alleviated lung damage (probably by blocking neutrophil infiltration), and increased the capacity of the antioxidant system.

Anti-inflammatory effects of α7-nicotinic ACh receptors are exerted through interactions with adenylyl cyclase-6

BACKGROUND AND PURPOSE

Nicotinic ACh receptors containing the α7 sub-unit (α7-nAChRs) suppress inflammation through a wide range of pathways in immune cells. These receptors are thus potentially involved in a number of inflammatory diseases. However, the detailed mechanisms underlying the anti-inflammatory effects of α7-nAChRs remain to be described.

EXPERIMENTAL APPROACH

Anti-inflammatory effects of α7-nAChR agonists were assessed in both murine macrophages (RAW 264.7) and bone marrow-derived macrophages (BMDM), stimulated with LPS, using immunoblotting, RT-PCR and luciferase reporter assays. The role of adenylyl cyclase-6 in the degradation of Toll-like receptor 4 (TLR4) following endocytosis, was explored via overexpression and knockdown. A mouse model of chronic obstructive pulmonary disease (COPD) induced by porcine pancreatic elastase was used to confirm key findings.

RESULTS

Anti-inflammatory effects of α7-nAChRs were largely dependent on adenylyl cyclase-6 activation, as knockdown of adenylyl cyclase-6 considerably reduced the effects of α7-nAChR agonists while adenylyl cyclase-6 overexpression promoted them. We found that α7-nAChRs and adenylyl cyclase-6 are co-localized in lipid rafts of macrophages and directly interact. Activation of adenylyl cyclase-6 led to increased degradation of TLR4. Administration of the α7-nAChR agonist PNU-282987 attenuated pathological and inflammatory end points in a mouse model of COPD.

CONCLUSION AND IMPLICATIONS

The α7-nAChRs inhibit inflammation through activating adenylyl cyclase-6 and promoting degradation of TLR4. The use of α7-nAChR agonists may represent a novel therapeutic approach for treating COPD and possibly other inflammatory diseases.

Increased Retinal Ganglion Cell Survival by Exogenous IL-2 Depends on IL-10, Dopamine D1 Receptors, and Classical IL-2/IL-2R Signaling Pathways

Interleukin-2 (IL-2) is a classical pro-inflammatory cytokine known to display neuroprotective roles in the central nervous system including the retina. In the present study, we investigate the molecular targets involved in the neurotrophic effect of IL-2 on retinal ganglion cells (RGC) after optic nerve axotomy. Analysis of retrograde labeling of RGC showed that common cell survival mediators, as Trk receptors, Src, PI3K, PKC, and intracellular calcium do not mediate the neurotrophic effect of IL-2 on RGC. No involvement of MAPK p38 was also observed. However, other MAPKs as MEK and JNK appear to be mediating this IL-2 effect. Our data also indicate that JAK2/3 are important intracellular proteins for the IL-2 effect. Interestingly, we demonstrate that the IL-2 effect depends on dopamine D1 receptors (D1R), the cAMP/PKA pathway, interleukin-10 (IL-10), and NF-κB, suggesting that RGC survival induced by IL-2 encompasses a molecular network of major complexity. In addition, treatment of retinal cells with recombinant IL-10 or 6-Cl-pb (D1R full agonist) was able to increase RGC survival similar to IL-2. Taken together, our results suggest that after optic nerve axotomy, the increase in RGC survival triggered by IL-2 is mediated by IL-10 and D1R along with the intracellular pathways of MAPKs, JAK/STAT, and cAMP/PKA.

IgG-Engineered Protective Antigen for Cytosolic Delivery of Proteins into Cancer Cells

Therapeutic immunotoxins composed of antibodies and bacterial toxins provide potent activity against malignant cells, but joining them with a defined covalent bond while maintaining the desired function is challenging. Here, we develop novel immunotoxins by dovetailing full-length immunoglobulin G (IgG) antibodies and nontoxic anthrax proteins, in which the C terminus of the IgG heavy chain is connected to the side chain of anthrax toxin protective antigen. This strategy enabled efficient conjugation of protective antigen variants to trastuzumab (Tmab) and cetuximab (Cmab) antibodies. The conjugates effectively perform intracellular delivery of edema factor and N terminus of lethal factor (LF_N) fused with diphtheria toxin and Ras/Rap1-specific endopeptidase. Each conjugate shows high specificity for cells expressing human epidermal growth factor receptor 2 (HER2) and epidermal growth factor receptor (EGFR), respectively, and potent activity across six Tmab- and Cmab-resistant cell lines. The conjugates also exhibit increased pharmacokinetics and pronounced in vivo safety, which shows promise for further therapeutic development.

Influence of pentoxifylline on gene expression of PAG1/ miR-1206/ SNHG14 in ischemic heart disease

The regulation by immune checkpoint is able to prevent excessive tissue damage caused by ischemia reperfusion (I/R); therefore, the study aims to investigate the behavior of phosphoprotein associated with glycosphingolipid-enriched microdomains 1 (PAG1) mRNA, miR-1206 and small nucleolar RNA host gene 14 (SNHG14) during I/R and intake of pentoxifylline (PTX) as a protective drug. The relative expression level of PAG1/miR-1206/SNHG14 was determined by qRT-PCR. Cardiac tissue levels of cytotoxic T-lymphocyte associated antigen 4 (CTLA4) and PAG1 protein expression were determined by ELISA technique. The regulatory T cells achieved by the flow cytometry. The results found that the relative expression of SNHG14 was significantly upregulated in I/R, but suppressed in PTX treated groups with enhancement of the relative expression level of miR-1206. The gene and protein expression of PAG1 were downregulated with effective doses of PTX. The results showed that (30 and 40 mg/kg bwt) PTX dose suppressed the CTLA4 development significantly. The mean of the regulatory T cell in PTX protective groups is significantly reduced at (p < 0.001) in a comparison with I/R group. Spearman's correlation analysis revealed a significant negative correlation between SNHG14 and miR-1206, but a significant positive correlation between SNHG14 and PAG1 in I/R heart tissue. The results indicated that miR-1206 and SNHG14 can be used as biomarkers with perfect sensitivity and specificity. Using PTX reduced cardiac tissue damage. SNHG14 and miR-1206 can be used as a diagnostic tool in I/R.

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Positive correlation between SNHG14 and PAG1 relative expression in I/R heart tissues.

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SNHG14 and miR-1206 can be used as a diagnostic tool in ischemia reperfusion.

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Negative correlation between SNHG14 and miR-1206.

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Using pentoxifylline as a protective drug renders cardiac tissues more resistance to ischemia.

Inhibition of matrix metalloproteinase-9 secretion by dimethyl sulfoxide and cyclic adenosine monophosphate in human monocytes

BACKGROUND

Matrix metalloproteinases (MMPs), including MMP-9, are an integral part of the immune response and are upregulated in response to a variety of stimuli. New details continue to emerge concerning the mechanistic and regulatory pathways that mediate MMP-9 secretion. There is significant evidence for regulation of inflammation by dimethyl sulfoxide (DMSO) and 3',5'-cyclic adenosine monophosphate (cAMP), thus investigation of how these two molecules may regulate both MMP-9 and tumor necrosis factor α (TNFα) secretion by human monocytes was of high interest. The hypothesis tested in this study was that DMSO and cAMP regulate MMP-9 and TNFα secretion by distinct mechanisms.

AIM

To investigate the regulation of lipopolysaccharide (LPS)-stimulated MMP-9 and tumor necrosis factor α secretion in THP-1 human monocytes by dimethyl sulfoxide and cAMP.

METHODS

The paper describes a basic research study using THP-1 human monocyte cells. All experiments were conducted at the University of Missouri-St. Louis in the Department of Chemistry and Biochemistry. Human monocyte cells were grown, cultured, and prepared for experiments in the University of Missouri-St. Louis Cell Culture Facility as per accepted guidelines. Cells were treated with LPS for selected exposure times and the conditioned medium was collected for analysis of MMP-9 and TNFα production. Inhibitors including DMSO, cAMP regulators, and anti-TNFα antibody were added to the cells prior to LPS treatment. MMP-9 secretion was analyzed by gel electrophoresis/western blot and quantitated by ImageJ software. TNFα secretion was analyzed by enzyme-linked immuno sorbent assay. All data is presented as the average and standard error for at least 3 trials. Statistical analysis was done using a two-tailed paired Student t-test. P values less than 0.05 were considered significant and designated as such in the Figures. LPS and cAMP regulators were from Sigma-Aldrich, MMP-9 standard and antibody and TNFα antibodies were from R&D Systems, and amyloid-β peptide was from rPeptide.

RESULTS

In our investigation of MMP-9 secretion from THP-1 human monocytes, we made the following findings. Inclusion of DMSO in the cell treatment inhibited LPS-induced MMP-9, but not TNFα, secretion. Inclusion of DMSO in the cell treatment at different concentrations inhibited LPS-induced MMP-9 secretion in a dose-dependent fashion. A cell-permeable cAMP analog, dibutyryl cAMP, inhibited both LPS-induced MMP-9 and TNFα secretion. Pretreatment of the cells with the adenylyl cyclase activator forskolin inhibited LPS-induced MMP-9 and TNFα secretion. Pretreatment of the cells with the general cAMP phosphodiesterase inhibitor IBMX reduced LPS-induced MMP-9 and TNFα in a dose-dependent fashion. Pre-treatment of monocytes with an anti-TNFα antibody blocked LPS-induced MMP-9 and TNFα secretion. Amyloid-β peptide induced MMP-9 secretion, which occurred much later than TNFα secretion. The latter two findings strongly suggested an upstream role for TNFα in mediating LPS-stimulate MMP-9 secretion.

CONCLUSION

The cumulative data indicated that MMP-9 secretion was a distinct process from TNFα secretion and occurred downstream. First, DMSO inhibited MMP-9, but not TNFα, suggesting that the MMP-9 secretion process was selectively altered. Second, cAMP inhibited both MMP-9 and TNFα with a similar potency, but at different monocyte cell exposure time points. The pattern of cAMP inhibition for these two molecules suggested that MMP-9 secretion lies downstream of TNFα and that TNFα may a key component of the pathway leading to MMP-9 secretion. This temporal relationship fit a model whereby early TNFα secretion directly led to later MMP-9 secretion. Lastly, antibody-blocking of TNFα diminished MMP-9 secretion, suggesting a direct link between TNFα secretion and MMP-9 secretion.

In vitro effects of citral on the human myometrium: Potential adjunct therapy to prevent preterm births

BACKGROUND

Premature infants contribute to infant morbidity and mortality especially in low resource settings. Information on tocolytic and/or anti-inflammatory effects of several plant extracts, such as citral, could help prevent preterm birth cases and reduce the number of preterm infants. The aim of this study was to evaluate the in vitro tocolytic and anti-inflammatory effect of citral on myometrial tissues of the human uterus.

METHODS

Myometrial samples from uteri obtained after hysterectomy were used in functional tests to evaluate the inhibitory effect of citral on PGF-2α induced contractions. The intracellular cyclic adenosine monophosphate (cAMP) levels generated in response to citral in human myometrial homogenates were measured by ELISAs. Forskolin was used as a positive control. The anti-inflammatory effect of citral was determined through the measurement of two pro-inflammatory cytokines, tumor necrosis factor-α (TNFα) and interleukin (IL)-1β, and the anti-inflammatory cytokine IL-10, in human myometrial explants stimulated with lipopolysaccharide (LPS).

RESULTS

Citral was able to induce a significant inhibition of PGF-2α induced contractions at the highest concentration level (p < .05). Citral caused a concentration-dependent increase in myometrial cAMP levels (p < .05) and a concentration-dependent decrease in LPS-induced TNFα and IL-1β production, while IL-10 production increased significantly (p < .05). The anti-inflammatory and tocolytic effects induced by citral could be associated with an increase in cAMP levels in human myometrial samples.

CONCLUSION

These properties place citral as a potentially safe and effective adjuvant agent in preterm birth cases, an obstetric and gynecological problem that requires urgent attention.

Inhibition of the Soluble Epoxide Hydrolase as an Analgesic Strategy: A Review of Preclinical Evidence

Chronic pain is a complicated condition which causes substantial physical, emotional, and financial impacts on individuals and society. However, due to high cost, lack of efficacy and safety problems, current treatments are insufficient. There is a clear unmet medical need for safe, nonaddictive and effective therapies in the management of pain. Epoxy-fatty acids (EpFAs), which are natural signaling molecules, play key roles in mediation of both inflammatory and neuropathic pain sensation. However, their molecular mechanisms of action remain largely unknown. Soluble epoxide hydrolase (sEH) rapidly converts EpFAs into less bioactive fatty acid diols in vivo; therefore, inhibition of sEH is an emerging therapeutic target to enhance the beneficial effect of natural EpFAs. In this review, we will discuss sEH inhibition as an analgesic strategy for pain management and the underlying molecular mechanisms.

Down-regulation of A3AR signaling by IL-6-induced GRK2 activation contributes to Th17 cell differentiation

IL-6-triggered Th17 cell expansion is responsible for the pathogenesis of many immune diseases including rheumatoid arthritis (RA). Traditionally, IL-6 induces Th17 cell differentiation through JAK-STAT3 signaling. In the present work, PKA inhibition reduces in vitro induction of Th17 cells, while IL-6 stimulation of T cells facilitates the internalization of A₃AR and increased cAMP production in a GRK2 dependent manner. Inhibition of GRK2 by paroxetine (PAR) or genetic depletion of GRK2 restored A₃AR distribution and prevented Th17 cell differentiation. Furthermore, in vivo PAR treatment effectively reduced the splenic Th17 cell proportion in a rat model of collagen-induced arthritis (CIA) which was accompanied by a significant improvement in clinical manifestations. These results indicate that IL-6-induced Th17 cell differentiation not only occurs through JAK-STAT3-RORγt but is also mediated through GRK2-A₃AR-cAMP-PKA-CREB/ICER-RORγt. This elucidates the significance of GRK2-controlled cAMP signaling in the differentiation of Th17 cells and its potential application in treating Th17-driven immune diseases such as RA.

Identification of Shared Genes and Pathways in Periodontitis and Type 2 Diabetes by Bioinformatics Analysis

INTRODUCTION

It is well known that the presence of diabetes significantly affects the progression of periodontitis and that periodontitis has negative effects on diabetes and diabetes-related complications. Although this two-way relationship between type 2 diabetes and periodontitis could be understood through experimental and clinical studies, information on common genetic factors would be more useful for the understanding of both diseases and the development of treatment strategies.

MATERIALS AND METHODS

Gene expression data for periodontitis and type 2 diabetes were obtained from the Gene Expression Omnibus database. After preprocessing of data to reduce heterogeneity, differentially expressed genes (DEGs) between disease and normal tissue were identified using a linear regression model package. Gene ontology and Kyoto encyclopedia of genes and genome pathway enrichment analyses were conducted using R package 'vsn'. A protein-protein interaction network was constructed using the search tool for the retrieval of the interacting genes database. We used molecular complex detection for optimal module selection. CytoHubba was used to identify the highest linkage hub gene in the network.

RESULTS

We identified 152 commonly DEGs, including 125 upregulated and 27 downregulated genes. Through common DEGs, we constructed a protein-protein interaction and identified highly connected hub genes. The hub genes were up-regulated in both diseases and were most significantly enriched in the Fc gamma R-mediated phagocytosis pathway.

DISCUSSION

We have identified three up-regulated genes involved in Fc gamma receptor-mediated phagocytosis, and these genes could be potential therapeutic targets in patients with periodontitis and type 2 diabetes.

Characterization of LY2775240, a selective phosphodiesterase-4 inhibitor, in nonclinical models and in healthy subjects

Abstract

LY2775240 is a highly selective, potent and orally‐administered inhibitor of phosphodiesterase 4 (PDE4), and is being investigated as a treatment option for inflammatory disorders, such as psoriasis. LY2775240 was investigated in rodent and rhesus monkey nonclinical models. Treatment with LY2775240 led to significant reductions in TNFα production, a marker of PDE4 engagement upon immune activation, in both nonclinical models. In the first part of a 2‐part first‐in‐human randomized study, a wide dose range of LY2775240 was safely evaluated and found to be well‐tolerated with common adverse events (AEs) of nausea, diarrhea, and headache. No serious AEs were reported. The pharmacokinetic profile of LY2775240 was well‐characterized, with a half‐life that can support once‐a‐day dosing. An ex vivo pharmacodynamic (PD) assay demonstrated dose‐dependent PDE4 target engagement as assessed by reduction in TNFα production. A 20 mg dose of LY2775240 led to near‐maximal TNFα inhibition in this PD assay in the first part of the study and was selected for comparison with the clinical dose of apremilast (30 mg) in the crossover, second part of this study. The 20 mg dose of LY2775240 demonstrated sustained maximal (50%–80%) inhibition of TNFα over all timepoints over the 24‐h duration. The comparator apremilast achieved peak inhibition of ~ 50% at only 4 h postdose with a return to about 10% inhibition within 12 h of dosing. In summary, the nonclinical data and safety, tolerability, and PK/PD data in healthy subjects supports further investigation of LY2775240 in inflammatory indications.

R848 or influenza virus can induce potent innate immune responses in the lungs of neonatal mice

Innate immune responses are important to protect the neonatal lung, which becomes exposed to commensal and pathogenic microorganisms immediately after birth, at a time when both the lung and the adaptive immune system are still developing. How immune cells in the neonatal lung respond to innate immune stimuli, including toll-like receptor (TLR) agonists, or viruses, is currently unclear. To address this, adult and neonatal mice were intranasally administered with various innate immune stimuli, respiratory syncytial virus (RSV) or influenza virus and cytokine and chemokine levels were quantified. The neonatal lungs responded weakly to RSV and most stimuli but more strongly than adult mice to R848 and influenza virus, both of which activate TLR7 and the inflammasome. Notably, neonatal lungs also contained higher levels of cAMP, a secondary messenger produced following adenosine receptor signaling, than adult lungs and increased responsiveness to R848 was observed in adult mice when adenosine was coadministered. Our data suggest that the neonatal lung may respond preferentially to stimuli that coactivate TLR7 and the inflammasome and that these responses may be amplified by extracellular adenosine. Improved understanding of regulation of immune responses in the neonatal lung can inform the development of vaccine adjuvants for the young.

Mitochondria, Oxidative Stress, cAMP Signalling and Apoptosis: A Crossroads in Lymphocytes of Multiple Sclerosis, a Possible Role of Nutraceutics

Multiple sclerosis (MS) is a complex inflammatory and neurodegenerative chronic disease that involves the immune and central nervous systems (CNS). The pathogenesis involves the loss of blood–brain barrier integrity, resulting in the invasion of lymphocytes into the CNS with consequent tissue damage. The MS etiology is probably a combination of immunological, genetic, and environmental factors. It has been proposed that T lymphocytes have a main role in the onset and propagation of MS, leading to the inflammation of white matter and myelin sheath destruction. Cyclic AMP (cAMP), mitochondrial dysfunction, and oxidative stress exert a role in the alteration of T lymphocytes homeostasis and are involved in the apoptosis resistance of immune cells with the consequent development of autoimmune diseases. The defective apoptosis of autoreactive lymphocytes in patients with MS, allows these cells to perpetuate, within the CNS, a continuous cycle of inflammation. In this review, we discuss the involvement in MS of cAMP pathway, mitochondria, reactive oxygen species (ROS), apoptosis, and their interaction in the alteration of T lymphocytes homeostasis. In addition, we discuss a series of nutraceutical compounds that could influence these aspects.

Apremilast Microemulsion as Topical Therapy for Local Inflammation: Design, Characterization and Efficacy Evaluation

Apremilast (APR) is a selective phosphodiesterase 4 inhibitor administered orally in the treatment of moderate-to-severe plaque psoriasis and active psoriatic arthritis. The low solubility and permeability of this drug hinder its dermal administration. The purpose of this study was to design and characterize an apremilast-loaded microemulsion (APR-ME) as topical therapy for local skin inflammation. Its composition was determined using pseudo-ternary diagrams. Physical, chemical and biopharmaceutical characterization were performed. Stability of this formulation was studied for 90 days. Tolerability of APR-ME was evaluated in healthy volunteers while its anti-inflammatory potential was studied using in vitro and in vivo models. A homogeneous formulation with Newtonian behavior and droplets of nanometric size and spherical shape was obtained. APR-ME released the incorporated drug following a first-order kinetic and facilitated drug retention into the skin, ensuring a local effect. Anti-inflammatory potential was observed for its ability to decrease the production of IL-6 and IL-8 in the in vitro model. This effect was confirmed in the in vivo model histologically by reduction in infiltration of inflammatory cells and immunologically by decrease of inflammatory cytokines IL-8, IL-17A and TNFα. Consequently, these results suggest that this formulation could be used as an attractive topical treatment for skin inflammation.

N-Docosahexanoylethanolamine Reduces Microglial Activation and Improves Hippocampal Plasticity in a Murine Model of Neuroinflammation

Chronic neuroinflammation is a common pathogenetic link in the development of various neurological and neurodegenerative diseases. Thus, a detailed study of neuroinflammation and the development of drugs that reduce or eliminate the negative effect of neuroinflammation on cognitive processes are among the top priorities of modern neurobiology. N-docosahexanoylethanolamine (DHEA, synaptamide) is an endogenous metabolite and structural analog of anandamide, an essential endocannabinoid produced from arachidonic acid. Our study aims to elucidate the pharmacological activity of synaptamide in lipopolysaccharide (LPS)-induced neuroinflammation. Memory deficits in animals were determined using behavioral tests. To study the effects of LPS (750 µg/kg/day, 7 days) and synaptamide (10 mg/kg/day, 7 days) on synaptic plasticity, long-term potentiation was examined in the CA1 area of acute hippocampal slices. The Golgi-Cox method allowed us to assess neuronal morphology. The production of inflammatory factors and receptors was assessed using ELISA and immunohistochemistry. During the study, functional, structural, and plastic changes within the hippocampus were identified. We found a beneficial effect of synaptamide on hippocampal synaptic plasticity and morphological characteristics of neurons. Synaptamide treatment recovered hippocampal neurogenesis, suppressed microglial activation, and significantly improved hippocampus-dependent memory. The basis of the phenomena described above is probably the powerful anti-inflammatory activity of synaptamide, as shown in our study and several previous works.

New putative insights into neprilysin (NEP)-dependent pharmacotherapeutic role of roflumilast in treating COVID-19

Nowadays, coronavirus disease 2019 (COVID-19) represents the most serious inflammatory respiratory disease worldwide. Despite many proposed therapies, no effective medication has yet been approved. Neutrophils appear to be the key mediator for COVID-19-associated inflammatory immunopathologic, thromboembolic and fibrotic complications. Thus, for any therapeutic agent to be effective, it should greatly block the neutrophilic component of COVID-19. One of the effective therapeutic approaches investigated to reduce neutrophil-associated inflammatory lung diseases with few adverse effects was roflumilast. Being a highly selective phosphodiesterase-4 inhibitors (PDE4i), roflumilast acts by enhancing the level of cyclic adenosine monophosphate (cAMP), that probably potentiates its anti-inflammatory action via increasing neprilysin (NEP) activity. Because activating NEP was previously reported to mitigate several airway inflammatory ailments; this review thoroughly discusses the proposed NEP-based therapeutic properties of roflumilast, which may be of great importance in curing COVID-19. However, further clinical studies are required to confirm this strategy and to evaluate its in vivo preventive and therapeutic efficacy against COVID-19.

Regulation of PD-L1 expression is a novel facet of cyclic-AMP-mediated immunosuppression

Cyclic-AMP (cAMP) exerts suppressive effects in the innate and adaptive immune system. The PD-1/PD-L1 immune checkpoint down-regulates T-cell activity. Here, we examined if these two immunosuppressive nodes intersect. Using normal and malignant lymphocytes from humans, and the phosphodiesterase 4b (Pde4b) knockout mouse, we found that cAMP induces PD-L1 transcription and protein expression. Mechanistically, we discovered that the cAMP effectors PKA and CREB induce the transcription/secretion of IL-10, IL-8 and IL-6, which initiate an autocrine loop that activates the JAK/STAT pathway and ultimately increase PD-L1 expression in the cell surface. This signaling axis is disarmed at two specific nodes in subsets of diffuse large B cell lymphoma, which may help explain the variable PD-L1 expression in these tumors. In vivo, we found that despite its immunosuppressive attributes, the PDE4 inhibitor roflumilast did not decrease the clinical activity of checkpoint inhibitors, an important clinical observation given the approved use of these agents in multiple diseases. In summary, we discovered that PD-L1 induction is a part of the repertoire of immunosuppressive actions mediated by cAMP, defined a cytokine-mediated autocrine loop that executes this action and, reassuringly, showed that PDE4 inhibition does not antagonize immune checkpoint blockade in an in vivo syngeneic lymphoma model.

Anti-Inflammatory Effect of Geniposide on Regulating the Functions of Rheumatoid Arthritis Synovial Fibroblasts via Inhibiting Sphingosine-1-Phosphate Receptors1/3 Coupling Gαi/Gαs Conversion

The activated Gα protein subunit (Gαs) and the inhibitory Gα protein subunit (Gαi) are involved in the signal transduction of G protein coupled receptors (GPCRs). Moreover, the conversion of Gαi/Gαs can couple with sphingosine-1-phosphate receptors (S1PRs) and have a critical role in rheumatoid arthritis (RA). Through binding to S1PRs, sphingosine-1-phosphate (S1P) leads to activation of the pro-inflammatory signaling in rheumatoid arthritis synovial fibroblasts (RASFs). Geniposide (GE) can alleviate RASFs dysfunctions to against RA. However, its underlying mechanism of action in RA has not been elucidated so far. This study aimed to investigate whether GE could regulate the biological functions of MH7A cells by inhibiting S1PR1/3 coupling Gαi/Gαs conversion. We use RASFs cell line, namely MH7A cells, which were obtained from the patient with RA and considered to be the main effector cells in RA. The cells were stimulated with S1P (5 μmol/L) and then were treated with or without different inhibitors: Gαi inhibitor pertussis toxin (0.1 μg/mL), S1PR1/3 inhibitor VPC 23019 (5 μmol/L), Gαs activator cholera toxin (1 μg/mL) and GE (25, 50, and 100 μmol/L) for 24 h. The results showed that GE may inhibit the abnormal proliferation, migration and invasion by inhibiting the S1P-S1PR1/3 signaling pathway and activating Gαs or inhibiting Gαi protein in MH7A cells. Additionally, GE could inhibit the release of inflammatory factors and suppress the expression of cAMP, which is the key factor of the conversion of Gαi and Gαs. GE could also restore the dynamic balance of Gαi and Gαs by suppressing S1PR1/3 and inhibiting Gαi/Gαs conversion, in a manner, we demonstrated that GE inhibited the activation of Gα downstream ERK protein as well. Taken together, our results indicated that down-regulation of S1PR1/3-Gαi/Gαs conversion may play a critical role in the effects of GE on RA and GE could be an effective therapeutic agent for RA.

Common issues among asthma, epilepsy, and schizophrenia: from inflammation to Ca2+/cAMP signalling

BACKGROUND

A large amount of evidence has described that asthma may be associated with a high epilepsy risk, and epilepsy may be linked with a high asthma risk, especially among children and individuals in their 30s. Curiously, asthma has also been associated with an increased risk for schizophrenia. Most interestingly, a bidirectional link between schizophrenia and epilepsy has also been established, and has been of interest for many years.

OBJECTIVE

Bearing in mind the experience of our group in the field of Ca2+/cAMP signalling pathways, this article discussed, beyond inflammation, the role of these signalling pathways in this link among epilepsy, asthma, and schizophrenia.

METHODS

Publications involving these signalling pathways, asthma, epilepsy, and schizophrenia (alone or combined) were collected by searching PubMed and EMBASE.

RESULTS AND CONCLUSION

There is a clear relationship between Ca2+ signalling, e.g. increased Ca2+ signals, and inflammatory responses. In addition to Ca2+, cAMP regulates pro- and anti-inflammatory responses. Then, beyond inflammation, the comprehension of the link among epilepsy, asthma and schizophrenia could improve the drug therapy.

N-Docosahexaenoylethanolamine Attenuates Neuroinflammation and Improves Hippocampal Neurogenesis in Rats with Sciatic Nerve Chronic Constriction Injury

Chronic neuropathic pain is a condition that causes both sensory disturbances and a variety of functional disorders, indicating the involvement of various brain structures in pain pathogenesis. One of the factors underlying chronic neuropathic pain is neuroinflammation, which is accompanied by microglial activation and pro-inflammatory factor release. N-docosahexaenoylethanolamine (DHEA, synaptamide) is an endocannabinoid-like metabolite synthesized endogenously from docosahexaenoic acid. Synaptamide exhibits anti-inflammatory activity and improves neurite outgrowth, neurogenesis, and synaptogenesis within the hippocampus. This study aims to evaluate the effects of synaptamide obtained by the chemical modification of DHA, extracted from the Far Eastern raw material Berryteuthis magister on neuroinflammatory response and hippocampal neurogenesis changes during neuropathic pain. The study of microglial protein and cytokine concentrations was performed using immunohistochemistry and ELISA. The brain lipid analysis was performed using the liquid chromatography-mass spectrometry technique. Behavioral experiments showed that synaptamide prevented neuropathic pain-associated sensory and behavioral changes, such as thermal allodynia, impaired locomotor activity, working and long-term memory, and increased anxiety. Synaptamide attenuated microglial activation, release of proinflammatory cytokines, and decrease in hippocampal neurogenesis. Lipid analysis revealed changes in the brain N-acylethanolamines composition and plasmalogen concentration after synaptamide administration. In conclusion, we show here that synaptamide may have potential for use in preventing or treating neuropathic cognitive pain and emotional effects.

Induction of Allograft Tolerance While Maintaining Immunity Against Microbial Pathogens: Does Coronin 1 Hold a Key?

Selective suppression of graft rejection while maintaining anti-pathogen responses has been elusive. Thus far, the most successful strategies to induce suppression of graft rejection relies on inhibition of T-cell activation. However, the very same mechanisms that induce allograft-specific T-cell suppression are also important for immunity against microbial pathogens as well as oncogenically transformed cells, resulting in significant immunosuppression-associated comorbidities. Therefore, defining the pathways that differentially regulate anti-graft versus antimicrobial T-cell responses may allow the development of regimen to induce allograft-specific tolerance. Recent work has defined a molecular pathway driven by the immunoregulatory protein coronin 1 that regulates the phosphodiesterase/cyclic adenosine monophosphate pathway and modulates T cell responses. Interestingly, disruption of coronin 1 promotes allograft tolerance while immunity towards a range of pathogenic microbes is maintained. Here, we briefly review the work leading up to these findings as well as their possible implications for transplantation medicine.

Multidisciplinary Management of the Adverse Effects of Apremilast

We present a series of general and specific recommendations based on pathophysiologic considerations for managing the most common adverse effects of apremilast that lead to treatment discontinuation: diarrhea, nausea, and headache. The recommendations are based on a review of the literature and the experience of a multidisciplinary team of 14 experts including dermatologists, rheumatologists, neurologists, gastroenterologists, pharmacists, and nurses. We propose a series of simple algorithms that include clinical actions and suggestions for pharmacologic treatment. The adverse effects of apremilast can be managed from a multidisciplinary approach. The purpose of optimizing management is to bring clinical benefits to patients.

Agrin induces long-term osteochondral regeneration by supporting repair morphogenesis

Cartilage loss leads to osteoarthritis, the most common cause of disability for which there is no cure. Cartilage regeneration, therefore, is a priority in medicine. We report that agrin is a potent chondrogenic factor and that a single intraarticular administration of agrin induced long-lasting regeneration of critical-size osteochondral defects in mice, with restoration of tissue architecture and bone-cartilage interface. Agrin attracted joint resident progenitor cells to the site of injury and, through simultaneous activation of CREB and suppression of canonical WNT signaling downstream of β-catenin, induced expression of the chondrogenic stem cell marker GDF5 and differentiation into stable articular chondrocytes, forming stable articular cartilage. In sheep, an agrin-containing collagen gel resulted in long-lasting regeneration of bone and cartilage, which promoted increased ambulatory activity. Our findings support the therapeutic use of agrin for joint surface regeneration.

Oxygenation and A2AR blockade to eliminate hypoxia/HIF-1α-adenosinergic immunosuppressive axis and improve cancer immunotherapy

The promising results of the first in-human clinical study using A2AR antagonists for treatment of renal cell carcinoma highlight two decades of research into the hypoxia-A2-adenosinergic pathway. Importantly, clinical responses have been observed in patients who previously progressed on anti-PD-1/PDL-1 therapy, emphasizing the clinical importance of targeting A2AR signaling in cancer immunotherapies. Recently, it has been shown that systemic oxygenation weakens all known stages of the hypoxia-A2-adenosinergic axis. Therefore, we advocate the clinical use of systemic oxygenation and oxygenation agents in combination with A2AR blockade to further improve cancer immunotherapies. This approach is expected to completely eliminate the upstream (hypoxia-HIF-1α) and downstream (adenosine-A2AR) stages of the immunosuppressive hypoxia-adenosinergic signaling axis. This might be a necessary strategy to maximize the therapeutic benefits of A2AR antagonists and increase susceptibility of tumors to cancer treatments.

Commentary: Phosphodiesterase 4 inhibitors as potential adjunct treatment targeting the cytokine storm in COVID-19

The most severe presentation of COVID-19 is characterized by a hyperinflammatory state attributed to the massive pro-inflammatory cytokine release, called "cytokine storm". Several specific anti-inflammatory/immunosuppressive agents are being evaluated by ongoing clinical trials; however, there is currently insufficient evidence for their efficacy and safety in COVID-19 treatment. Given the role of phosphodiesterase 4 (PDE) 4 and cyclic adenosine monophosphate in the inflammatory response, we hypothesize that selective PDE4 inhibition may attenuate the cytokine storm in COVID-19, through the upstream inhibition of pro-inflammatory molecules, particularly TNF-α, and the regulation of the pro-inflammatory/anti-inflammatory balance. Conversely, other anti-cytokine agents lead to the downstream inhibition of specific targets, such as IL-1, IL-6 or TNF-α, and may not be efficient in blocking the cytokine storm, once it has been triggered. Due to their mechanism of action targeting an early stage of the inflammatory response and ameliorating lung inflammation, we believe that selective PDE4 inhibitors may represent a promising treatment option for the early phase of COVID-19 pneumonia before the cytokine storm and severe multiorgan dysfunction take place. Furthermore, PDE4 inhibitors present several advantages including an excellent safety profile; the oral route of administration; the convenient dosing; and beneficial metabolic properties. Interestingly, obesity and diabetes mellitus type 2 have been reported to be risk factors for the severity of COVID-19. Therefore, randomized clinical trials of PDE4 inhibitors are necessary to explore their potential therapeutic effect as an adjunct to supportive measures and other therapeutic regiments.

A Review on Currently Available Potential Therapeutic Options for COVID-19

A series of unexplained pneumonia cases currently were first reported in December 2019 in Wuhan, China. Official names have been announced for the virus responsible, previously known as "2019 novel coronavirus" and the diseases it causes are, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and coronavirus disease (COVID-19), respectively. Despite great efforts worldwide to control SARS-CoV-2, the spread of the virus has reached a pandemic. Infection prevention and control of this virus is the primary concern of public health officials and professionals. Currently, several therapeutic options for COVID-19 are proposed and vaccine development has been initiated for prevention purposes. In this review, we will discuss the most recent evidence about the current potential treatment options including anti-inflammatory drugs, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, nucleoside analogs, protease inhibitors, monoclonal antibodies, and convalescent plasma therapy. Some other agents such as vitamin D and melatonin, which were recommended as potential adjuvant treatments for COVID-19 infection are also presented. Moreover, the potential use of convalescent plasma for treatment of COVID-19 infection was described. Furthermore, in the next part of the current review, various vaccination approaches against COVID-19 including whole virus vaccines, recombinant subunit vaccine, DNA vaccines, and mRNA vaccines are discussed.

Emerging treatments for atopic dermatitis

Increasing information on the pathophysiology of atopic dermatitis (AD), accumulating data on cellular and molecular pathways in immunological reactions and inflammation, and the expansion of biotechnology and pharmacology have collectively contributed to the development of new pharmacological agents for AD. Novel pharmaceutical agents, including biologics targeting cytokines, which play pathogenetic roles in AD, for example, interleukin (IL)-4, IL-13, IL-31 and IL-22, Janus kinase inhibitors, phosphodiesterase 4 inhibitors and histamine H₄ receptor antagonists, have been approved or are being developed. These agents are expected to be effective in AD patients with skin signs and/or symptoms that are refractory to conventional treatments. The development of novel drugs will accompany the use of predictive biomarkers for each agent in order to optimize treatment in each patient. Convenient tools that support self-decision-making by patients to reflect their preferences, which will increase treatment satisfaction and adherence, are also anticipated.

Cyclic AMP in dendritic cells: A novel potential target for disease-modifying agents in asthma and other allergic disorders

Allergic diseases are immune disorders that are a global health problem, affecting a large portion of the world's population. Allergic asthma is a heterogeneous disease that alters the biology of the airway. A substantial portion of patients with asthma do not respond to conventional therapies; thus, new and effective therapeutics are needed. Dendritic cells (DCs), antigen presenting cells that regulate helper T cell differentiation, are key drivers of allergic inflammation but are not the target of current therapies. Here we review the role of dendritic cells in allergic conditions and propose a disease-modifying strategy for treating allergic asthma: cAMP-mediated inhibition of dendritic cells to blunt allergic inflammation. This approach contrasts with current treatments that focus on treating clinical manifestations of airway inflammation. Disease-modifying agents that target cAMP and its signalling pathway in dendritic cells may provide a novel means to treat asthma and other allergic diseases.

An NMR based phosphodiesterase assay

We propose a phosphodiesterase assay based on 1D ¹H NMR to monitor the hydrolysis of cyclic nucleotides directly, without requiring tags or the addition of exogenous reagents. The method is suitable to measure phosphodiesterase K_M and k_cat parameters and to identify phosphodiesterase inhibitors.

Mucosal Profiling of Pediatric-Onset Colitis and IBD Reveals Common Pathogenics and Therapeutic Pathways

Pediatric-onset colitis and inflammatory bowel disease (IBD) have significant effects on the growth of infants and children, but the etiopathogenesis underlying disease subtypes remains incompletely understood. Here, we report single-cell clustering, immune phenotyping, and risk gene analysis for children with undifferentiated colitis, Crohn's disease, and ulcerative colitis. We demonstrate disease-specific characteristics, as well as common pathogenesis marked by impaired cyclic AMP (cAMP)-response signaling. Specifically, infiltration of PDE4B- and TNF-expressing macrophages, decreased abundance of CD39-expressing intraepithelial T cells, and platelet aggregation and release of 5-hydroxytryptamine at the colonic mucosae were common in colitis and IBD patients. Targeting these pathways by using the phosphodiesterase inhibitor dipyridamole restored immune homeostasis and improved colitis symptoms in a pilot study. In summary, comprehensive analysis of the colonic mucosae has uncovered common pathogenesis and therapeutic targets for children with colitis and IBD.

Phosphodiesterase 4B: Master Regulator of Brain Signaling

Phosphodiesterases (PDEs) are the only superfamily of enzymes that have the ability to break down cyclic nucleotides and, as such, they have a pivotal role in neurological disease and brain development. PDEs have a modular structure that allows targeting of individual isoforms to discrete brain locations and it is often the location of a PDE that shapes its cellular function. Many of the eleven different families of PDEs have been associated with specific diseases. However, we evaluate the evidence, which suggests the activity from a sub-family of the PDE4 family, namely PDE4B, underpins a range of important functions in the brain that positions the PDE4B enzymes as a therapeutic target for a diverse collection of indications, such as, schizophrenia, neuroinflammation, and cognitive function.

MicroRNA expression profile in chronic nonbacterial prostatitis revealed by next-generation small RNA sequencing

MicroRNAs (miRNAs) are considered to be involved in the pathogenic initiation and progression of chronic nonbacterial prostatitis (CNP); however, the comprehensive expression profile of dysregulated miRNAs, relevant signaling pathways, and core machineries in CNP have not been fully elucidated. In the current research, CNP rat models were established through the intraprostatic injection of carrageenan into the prostate. Then, next-generation sequencing was performed to explore the miRNA expression profile in CNP. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) bioinformatical analyses were conducted to reveal the enriched biological processes, molecular functions, and cellular components and signaling pathways. As a result, 1224, 1039, and 1029 known miRNAs were annotated in prostate tissues from the blank control (BC), normal saline injection (NS), and carrageenan injection (CAR) groups (n = 3 for each group), respectively. Among them, 84 miRNAs (CAR vs BC) and 70 miRNAs (CAR vs NS) with significantly different expression levels were identified. Compared with previously reported miRNAs with altered expression in various inflammatory diseases, the majority of deregulated miRNAs in CNP, such as miR-146b-5p, miR-155-5p, miR-150-5p, and miR-139-5p, showed similar expression patterns. Moreover, bioinformatics analyses have enriched mitogen-activated protein kinase (MAPK), cyclic adenosine monophosphate (cAMP), endocytosis, mammalian target of rapamycin (mTOR), and forkhead box O (FoxO) signaling pathways. These pathways were all involved in immune response, which indicates the critical regulatory role of the immune system in CNP initiation and progression. Our investigation has presented a global view of the differentially expressed miRNAs and potential regulatory networks containing their target genes, which may be helpful for identifying the novel mechanisms of miRNAs in immune regulation and effective target-specific theragnosis for CNP.

Exploring Biased Agonism at FPR1 as a Means to Encode Danger Sensing

Ligand-based selectivity in signal transduction (biased signaling) is an emerging field of G protein-coupled receptor (GPCR) research and might allow the development of drugs with targeted activation profiles. Human formyl peptide receptor 1 (FPR1) is a GPCR that detects potentially hazardous states characterized by the appearance of N-formylated peptides that originate from either bacteria or mitochondria during tissue destruction; however, the receptor also responds to several non-formylated agonists from various sources. We hypothesized that an additional layer of FPR signaling is encoded by biased agonism, thus allowing the discrimination of the source of threat. We resorted to the comparative analysis of FPR1 agonist-evoked responses across three prototypical GPCR signaling pathways, i.e., the inhibition of cAMP formation, receptor internalization, and ERK activation, and analyzed cellular responses elicited by several bacteria- and mitochondria-derived ligands. We also included the anti-inflammatory annexinA1 peptide Ac2-26 and two synthetic ligands, the W-peptide and the small molecule FPRA14. Compared to the endogenous agonists, the bacterial agonists displayed significantly higher potencies and efficacies. Selective pathway activation was not observed, as both groups were similarly biased towards the inhibition of cAMP formation. The general agonist bias in FPR1 signaling suggests a source-independent pathway selectivity for transmission of pro-inflammatory danger signaling.

Regulating cellular cyclic adenosine monophosphate: "Sources," "sinks," and now, "tunable valves"

A number of hormones and growth factors stimulate target cells via the second messenger pathways, which in turn regulate cellular phenotypes. Cyclic adenosine monophosphate (cAMP) is a ubiquitous second messenger that facilitates numerous signal transduction pathways; its production in cells is tightly balanced by ligand-stimulated receptors that activate adenylate cyclases (ACs), that is, "source" and by phosphodiesterases (PDEs) that hydrolyze it, that is, "sinks." Because it regulates various cellular functions, including cell growth and differentiation, gene transcription and protein expression, the cAMP signaling pathway has been exploited for the treatment of numerous human diseases. Reduction in cAMP is achieved by blocking "sources"; however, elevation in cAMP is achieved by either stimulating "source" or blocking "sinks." Here we discuss an alternative paradigm for the regulation of cellular cAMP via GIV/Girdin, the prototypical member of a family of modulators of trimeric GTPases, Guanine nucleotide Exchange Modulators (GEMs). Cells upregulate or downregulate cellular levels of GIV-GEM, which modulates cellular cAMP via spatiotemporal mechanisms distinct from the two most often targeted classes of cAMP modulators, "sources" and "sinks." A network-based compartmental model for the paradigm of GEM-facilitated cAMP signaling has recently revealed that GEMs such as GIV serve much like a "tunable valve" that cells may employ to finetune cellular levels of cAMP. Because dysregulated signaling via GIV and other GEMs has been implicated in multiple disease states, GEMs constitute a hitherto untapped class of targets that could be exploited for modulating aberrant cAMP signaling in disease states. This article is categorized under: Models of Systems Properties and Processes > Mechanistic Models Biological Mechanisms > Cell Signaling.

Single-Cell Encapsulation via Click-Chemistry Alters Production of Paracrine Factors from Neural Progenitor Cells

Extracellular matrix (ECM) properties affect multiple cellular processes such as cell survival, proliferation, and protein synthesis. Thus, a polymeric-cell delivery system with the ability to manipulate the extracellular environment can act as a fundamental regulator of cell function. Given the promise of stem cell therapeutics, a method to uniformly enhance stem cell function, in particular trophic factor release, can prove transformative in improving efficacy and increasing feasibility by reducing the total number of cells required. Herein, a click-chemistry powered 3D, single-cell encapsulation method aimed at synthesizing a polymeric coating with the optimal thickness around neural progenitor cells is introduced. Polymer encapsulation of neural stem cells significantly increases the release of neurotrophic factors such as VEGF and CNTF. Cell encapsulation with a soft extracellular polymer upregulates the ADCY8-cAMP pathway, suggesting a mechanism for the increase in paracrine factors. Hence, the described single-cell encapsulation technique can emerge as a translatable, nonviral cell modulation method and has the potential to improve stem cells' therapeutic effect.

Anti-Allergic and Anti-Inflammatory Effects of Undecane on Mast Cells and Keratinocytes

The critical roles of keratinocytes and resident mast cells in skin allergy and inflammation have been highlighted in many studies. Cyclic adenosine monophosphate (cAMP), the intracellular second messenger, has also recently emerged as a target molecule in the immune reaction underlying inflammatory skin conditions. Here, we investigated whether undecane, a naturally occurring plant compound, has anti-allergic and anti-inflammatory activities on sensitized rat basophilic leukemia (RBL-2H3) mast cells and HaCaT keratinocytes and we further explored the potential involvement of the cAMP as a molecular target for undecane. We confirmed that undecane increased intracellular cAMP levels in mast cells and keratinocytes. In sensitized mast cells, undecane inhibited degranulation and the secretion of histamine and tumor necrosis factor α (TNF-α). In addition, in sensitized keratinocytes, undecane reversed the increased levels of p38 phosphorylation, nuclear factor kappaB (NF-κB) transcriptional activity and target cytokine/chemokine genes, including thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC) and interleukin-8 (IL-8). These results suggest that undecane may be useful for the prevention or treatment of skin inflammatory disorders, such as atopic dermatitis, and other allergic diseases.

Small molecules under development for psoriasis: on the road to the individualized therapies

Psoriasis is an incurable cutaneous illness characterized by the presence of well-delimited reddish plaques and silvery-white dry scales. So far, there is a limited understanding of its pathogenesis, though recent discoveries on the immunological, genetic and molecular aspects of this disease have significantly contributed to the identification of new targets and the development of novel drugs. Despite these advances, many patients are still dissatisfied, so to improve patient satisfaction, reliability, and clinical outcomes, the individualization of the treatments for this disease becomes a necessity. This review summarizes recent findings related to psoriasis pathogenesis and describes new small molecules and targets recently identified as promising for treatments. Additionally, the current status, challenges and the future directions for achieving individualized therapy for this disease and the need for more collaborative studies are discussed. The individualization of treatments for psoriasis, rather than a goal, is analyzed as a process where a dynamic integration between the needs and characteristics of the patients, the pharmacological progress, and the clinical decisions takes place.

Molecular docking and network connections of active compounds from the classical herbal formula Ding Chuan Tang

Background

Ding Chuan Tang (DCT), a traditional Chinese herbal formula, has been consistently prescribed for the therapeutic management of wheezing and asthma-related indications since the Song Dynasty (960–1279 AD). This study aimed to identify molecular network pharmacology connections to understand the biological asthma-linked mechanisms of action of DCT and potentially identify novel avenues for asthma drug development.

Methods

Employing molecular docking (AutoDock Vina) and computational analysis (Cytoscape 3.6.0) strategies for DCT compounds permitted examination of docking connections for proteins that were targets of DCT compounds and asthma genes. These identified protein targets were further analyzed to establish and interpret network connections associated with asthma disease pathways.

Results

A total of 396 DCT compounds and 234 asthma genes were identified through database search. Computational molecular docking of DCT compounds identified five proteins (ESR1, KDR, LTA4H, PDE4D and PPARG) mutually targeted by asthma genes and DCT compounds and 155 docking connections associated with cellular pathways involved in the biological mechanisms of asthma.

Conclusions

DCT compounds directly target biological pathways connected with the pathogenesis of asthma including inflammatory and metabolic signaling pathways.

Advances in Discovery of PDE10A Inhibitors for CNS-Related Disorders. Part 1: Overview of the Chemical and Biological Research

Phosphodiesterase 10A (PDE10A) is a double substrate enzyme that hydrolyzes second messenger molecules such as cyclic-3',5'-adenosine monophosphate (cAMP) and cyclic-3',5'-guanosine monophosphate (cGMP). Through this process, PDE10A controls intracellular signaling pathways in the mammalian brain and peripheral tissues. Pharmacological, biochemical, and anatomical data suggest that disorders in the second messenger system mediated by PDE10A may contribute to impairments in the central nervous system (CNS) function, including cognitive deficits as well as disturbances of behavior, emotion processing, and movement. This review provides a detailed description of PDE10A and the recent advances in the design of selective PDE10A inhibitors. The results of preclinical studies regarding the potential utility of PDE10A inhibitors for the treatment of CNS-related disorders, such as schizophrenia as well as Huntington's and Parkinson's diseases are also summarized.

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.

Comparative Assessment of the New PDE7 Inhibitor - GRMS-55 and Lisofylline in Animal Models of Immune-Related Disorders: A PK/PD Modeling Approach

Purpose

This study aimed to assess the activity of two phosphodiesterase (PDE) inhibitors, namely GRMS-55 and racemic lisofylline ((±)-LSF)) in vitro and in animal models of immune-mediated disorders.

Methods

Inhibition of human recombinant (hr)PDEs and TNF-alpha release from LPS-stimulated whole rat blood by the studied compounds were assessed in vitro. LPS-induced endotoxemia, concanavalin A (ConA)-induced hepatitis, and collagen-induced arthritis (CIA) animal models were used for in vivo evaluation. The potency of the investigated compounds was evaluated using PK/PD and PK/PD/disease progression modeling.

Results

GRMS-55 is a potent hrPDE7A and hrPDE1B inhibitor, while (±)-LSF most strongly inhibits hrPDE3A and hrPDE4B. GRMS-55 decreased TNF-alpha levels in vivo and CIA progression with IC₅₀ of 1.06 and 0.26 mg/L, while (±)-LSF with IC₅₀ of 5.80 and 1.06 mg/L, respectively. Moreover, GRMS-55 significantly ameliorated symptoms of ConA-induced hepatitis.

Conclusions

PDE4B but not PDE4D inhibition appears to be mainly engaged in anti-inflammatory activity of the studied compounds. GRMS-55 and (±)-LSF seem to be promising candidates for future studies on the treatment of immune-related diseases. The developed PK/PD models may be used to assess the anti-inflammatory and anti-arthritic potency of new compounds for the treatment of rheumatoid arthritis and other inflammatory disorders.

Electronic supplementary material

The online version of this article (10.1007/s11095-019-2727-z) contains supplementary material, which is available to authorized users.

Invasion of microglia/macrophages and granulocytes into the Mauthner axon myelin sheath following spinal cord injury of the adult goldfish, Carassius auratus

Rapid activation of resident glia occurs after spinal cord injury. Somewhat later, innate and adaptive immune responses occur with the invasion of peripheral immune cells into the wound site. The activation of resident and peripheral immune cells has been postulated to play harmful as well as beneficial roles in the regenerative process. Mauthner cells, large identifiable neurons located in the hindbrain of most fish and amphibians, provided the opportunity to study the morphological relationship between reactive cells and Mauthner axons (M-axons) severed by spinal cord crush or by selective axotomy. After crossing in the hindbrain, the M-axons of adult goldfish, Carassius auratus, extend the length of the spinal cord. Following injury, the M-axon undergoes retrograde degeneration within its myelin sheath creating an axon-free zone (proximal dieback zone). Reactive cells invade the wound site, enter the axon-free dieback zone and are observed in the vicinity of the retracted M-axon tip as early as 3 hr postinjury. Transmission electron microscopy allowed the detection of microglia/macrophages and granulocytes, some of which appear to be neutrophil-like, at each of these locations. We believe that this is the first report of the invasion of such cells within the myelin sheath of an identifiable axon in the vertebrate central nervous system (CNS). We speculate that microglia/macrophages and granulocytes that are attracted within a few hours to the damaged M-axon are part of an inflammatory response that allows phagocytosis of debris and plays a role in the regenerative process. Our results provide the baseline from which to utilize immunohistochemical and genetic approaches to elucidate the role of non-neuronal cells in the regenerative process of a single axon in the vertebrate CNS.

GPR110 (ADGRF1) mediates anti-inflammatory effects of N-docosahexaenoylethanolamine

Background

Neuroinflammation is a widely accepted underlying condition for various pathological processes in the brain. In a recent study, synaptamide, an endogenous metabolite derived from docosahexaenoic acid (DHA, 22:6n-3), was identified as a specific ligand to orphan adhesion G-protein-coupled receptor 110 (GPR110, ADGRF1). Synaptamide has been shown to suppress lipopolysaccharide (LPS)-induced neuroinflammation in mice, but involvement of GPR110 in this process has not been established. In this study, we investigated the possible immune regulatory role of GPR110 in mediating the anti-neuroinflammatory effects of synaptamide under a systemic inflammatory condition.

Methods

For in vitro studies, we assessed the role of GPR110 in synaptamide effects on LPS-induced inflammatory responses in adult primary mouse microglia, immortalized murine microglial cells (BV2), primary neutrophil, and peritoneal macrophage by using quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA) as well as neutrophil migration and ROS production assays. To evaluate in vivo effects, wild-type (WT) and GPR110 knock-out (KO) mice were injected with LPS intraperitoneally (i.p.) or TNF intravenously (i.v.) followed by synaptamide (i.p.), and expression of proinflammatory mediators was measured by qPCR, ELISA, and western blot analysis. Activated microglia in the brain and NF-kB activation in cells were examined microscopically after immunostaining for Iba-1 and RelA, respectively.

Results

Intraperitoneal (i.p.) administration of LPS increased TNF and IL-1β in the blood and induced pro-inflammatory cytokine expression in the brain. Subsequent i.p. injection of the GPR110 ligand synaptamide significantly reduced LPS-induced inflammatory responses in wild-type (WT) but not in GPR110 knock-out (KO) mice. In cultured microglia, synaptamide increased cAMP and inhibited LPS-induced proinflammatory cytokine expression by inhibiting the translocation of NF-κB subunit RelA into the nucleus. These effects were abolished by blocking synaptamide binding to GPR110 using an N-terminal targeting antibody. GPR110 expression was found to be high in neutrophils and macrophages where synaptamide also caused a GPR110-dependent increase in cAMP and inhibition of LPS-induced pro-inflammatory mediator expression. Intravenous injection of TNF, a pro-inflammatory cytokine that increases in the circulation after LPS treatment, elicited inflammatory responses in the brain which were dampened by the subsequent injection (i.p.) of synaptamide in a GPR110-dependent manner.

Conclusion

Our study demonstrates the immune-regulatory function of GPR110 in both brain and periphery, collectively contributing to the anti-neuroinflammatory effects of synaptamide under a systemic inflammatory condition. We suggest GPR110 activation as a novel therapeutic strategy to ameliorate inflammation in the brain as well as periphery.

Novel phosphodiesterases inhibitors from the group of purine-2,6-dione derivatives as potent modulators of airway smooth muscle cell remodelling

Airway remodelling (AR) is an important pathological feature of chronic asthma and chronic obstructive pulmonary disease. The etiology of AR is complex and involves both lung structural and immune cells. One of the main contributors to airway remodelling is the airway smooth muscle (ASM), which is thickened by asthma, becomes more contractile and produces more extracellular matrix. As a second messenger, adenosine 3',5'-cyclic monophosphate (cAMP) has been shown to contribute to ASM cell (ASMC) relaxation as well as to anti-remodelling effects in ASMC. Phosphodiesterase (PDE) inhibitors have drawn attention as an interesting new group of potential anti-inflammatory and anti-remodelling drugs. Recently, new hydrazide and amide purine-2,6-dione derivatives with anti-inflammatory properties have been synthesized by our team (compounds 1 and 2). We expanded our study of their PDE selectivity profile, ability to increase intracellular cAMP levels, metabolic stability and, above all, their capacity to modulate cell responses associated with ASMC remodelling. The results show that both compounds have subtype specificity for several PDE isoforms (including inhibition of PDE1, PDE3, PDE4 and PDE7). Interestingly, such combined PDE subtype inhibition exerts improved anti-remodelling efficacies against several ASMC-induced responses such as proliferation, contractility, extracellular matrix (ECM) protein expression and migration when compared to other non-selective and selective PDE inhibitors. Our findings open novel perspectives in the search for new chemical entities with dual anti-inflammatory and anti-remodelling profiles in the group of purine-2,6-dione derivatives as broad-spectrum PDE inhibitors.