The Chemically-Modified Tetracycline COL-3 and Its Parent Compound Doxycycline Prevent Microglial Inflammatory Responses by Reducing Glucose-Mediated Oxidative Stress

We used mouse microglial cells in culture activated by lipopolysaccharide (LPS) or α-synuclein amyloid aggregates (αSa) to study the anti-inflammatory effects of COL-3, a tetracycline derivative without antimicrobial activity. Under LPS or αSa stimulation, COL-3 (10, 20 µM) efficiently repressed the induction of the microglial activation marker protein Iba-1 and the stimulated-release of the pro-inflammatory cytokine TNF-α. COL-3′s inhibitory effects on TNF-α were reproduced by the tetracycline antibiotic doxycycline (DOX; 50 µM), the glucocorticoid dexamethasone, and apocynin (APO), an inhibitor of the superoxide-producing enzyme NADPH oxidase. This last observation suggested that COL-3 and DOX might also operate themselves by restraining oxidative stress-mediated signaling events. Quantitative measurement of intracellular reactive oxygen species (ROS) levels revealed that COL-3 and DOX were indeed as effective as APO in reducing oxidative stress and TNF-α release in activated microglia. ROS inhibition with COL-3 or DOX occurred together with a reduction of microglial glucose accumulation and NADPH synthesis. This suggested that COL-3 and DOX might reduce microglial oxidative burst activity by limiting the glucose-dependent synthesis of NADPH, the requisite substrate for NADPH oxidase. Coherent with this possibility, the glycolysis inhibitor 2-deoxy-D-glucose reproduced the immunosuppressive action of COL-3 and DOX in activated microglia. Overall, we propose that COL-3 and its parent compound DOX exert anti-inflammatory effects in microglial cells by inhibiting glucose-dependent ROS production. These effects might be strengthened by the intrinsic antioxidant properties of DOX and COL-3 in a self-reinforcing manner.

Substrate binding modes of purine and pyrimidine nucleotides to human ecto-5′-nucleotidase (CD73) and inhibition by their bisphosphonic acid derivatives

Human ecto-5-nucleotidase (CD73) is involved in purinergic signalling, which influences a diverse range of biological processes. CD73 hydrolyses AMP and is the major control point for the levels of extracellular adenosine. Inhibitors of CD73 thus block the immunosuppressive action of adenosine, a promising approach for cancer immunotherapy. Interestingly, ADP and ATP are competitive inhibitors of CD73, with the most potent small-molecule inhibitors to date being non-hydrolysable ADP analogues. While AMP is the major substrate of the enzyme, CD73 has been reported to hydrolyse other 5′-nucleoside monophosphates. Based on a fragment screening campaign at the BESSY II synchrotron, we present the binding modes of various deoxyribo- and ribonucleoside monophosphates and of four additional fragments binding to the nucleoside binding site of the open form of the enzyme. Kinetic analysis of monophosphate hydrolysis shows that ribonucleotide substrates are favoured over their deoxyribose equivalents with AMP being the best substrate. We characterised the initial step of AMP hydrolysis, the binding mode of AMP to the open conformation of CD73 and compared that to other monophosphate substrates. In addition, the inhibitory activity of various bisphosphonic acid derivatives of nucleoside diphosphates was determined. Although AMPCP remains the most potent inhibitor, replacement of the adenine base with other purines or with pyrimidines increases the Ki value only between twofold and sixfold. On the other hand, these nucleobases offer new opportunities to attach substituents for improved pharmacological properties.

PGE2 displays immunosuppressive effects during human active tuberculosis

Prostaglandin E2 (PGE2), an active lipid compound derived from arachidonic acid, regulates different stages of the immune response of the host during several pathologies such as chronic infections or cancer. In fact, manipulation of PGE2 levels was proposed as an approach for countering the Type I IFN signature of tuberculosis (TB). However, very limited information regarding the PGE2 pathway in patients with active TB is currently available. In the present work, we demonstrated that PGE2 exerts a potent immunosuppressive action during the immune response of the human host against Mycobacterium tuberculosis (Mtb) infection. Actually, we showed that PGE2 significantly reduced the surface expression of several immunological receptors, the lymphoproliferation and the production of proinflammatory cytokines. In addition, PGE2 promoted autophagy in monocytes and neutrophils cultured with Mtb antigens. These results suggest that PGE2 might be attenuating the excessive inflammatory immune response caused by Mtb, emerging as an attractive therapeutic target. Taken together, our findings contribute to the knowledge of the role of PGE2 in the human host resistance to Mtb and highlight the potential of this lipid mediator as a tool to improve anti-TB treatment.

PGE2 Displays Immunosuppressive Effects During Human Active Tuberculosis

Prostaglandin E2 (PGE2), an active lipid compound derived from arachidonic acid, regulates different stages of the immune response of the host during several pathologies such as chronic infections or cancer. In fact, manipulation of PGE2 levels was proposed as an approach for countering the Type I IFN signature of tuberculosis (TB). However, very limited information regarding the PGE2 pathway in patients with active TB is currently available. In the present work, we demonstrated that PGE2 exerts a potent immunosuppressive action during the immune response of the human host against Mycobacterium tuberculosis (Mtb) infection. Actually, we showed that PGE2 significantly reduced lymphoproliferation, the production of proinflammatory cytokines, and the surface expression of several immunological receptors. On the other hand, PGE2 promoted autophagy in monocytes and neutrophils cultured with Mtb antigens. These results suggest that PGE2 might be attenuating the excessive inflammatory immune response caused by Mtb, emerging as an attractive therapeutic target. Taken together, our findings contribute to the knowledge of the role of PGE2 in the human host resistance to Mtb and highlight the potential of this lipid mediator as a tool to improve anti-TB treatment.

Topical Corticosteroids in Treatment of Atopic Dermatitis: An Overview of Their Current Status

Atopic dermatitis (AD) is a common skin disease characterized by epidermal changes with immune regulatory abnormalities. The pathogenesis of AD involves skin barrier defects, genetic factors and immune deregulation. The AD therapy includes skin hydration, anti-inflammatory agents, antibacterial medications and treatment of pruritus. Currently, topical corticosteroids (TCs) are the most frequently used drugs for the treatment of AD due to their potent immunosuppressive action. However, TCs are associated with several local and systemic side effects. The topical steroid addiction and phobia are among the major challenges with TC therapy. Over the years, efforts are being made to reduce side effects which involve adjustment of dosing, minimizing use in vulnerable areas, avoiding prolonged drug usage and application of novel drug delivery systems. The present review provides an overview of the current and upcoming delivery systems of TCs along with novel approaches being employed to improve the drug delivery in the treatment of AD.

Isolation, Structural Characterization and Identification of Major Constituents in Ephedra foliata Naturally Growing in Iraq by TLC, GC-MS and UPLC-ESI-MS/MS

The aerial part of Ephedra foliata Family Ephedraceae have long been used in traditional medicine and now Ephedra species have medicinal, ecological, and commercial value. The variety of pharmacological actions of this plant is due to its chemical constituents. Ephedrine and related alkaloids; are the newly potential medicinal value of Ephedra supplements for weight loss or performance improvement. Other pharmacological actions like antibacterial and antifungal effects of the phenolic acid compounds, the immunosuppressive action of the polysaccharides, and the antitumor action of flavonoids. The genus of this plant wildly distributed throughout asia, america, europe, and north africa. Aim of study: this study is to screen the phytochemical constituents due to the importance of pharmacological actions of this plant. Methods: the aerial part of E. foliata was macerated in 80% ethanol for 9 days and fractionated by n-hexane, chloroform, ethyl acetate, and n-butanol. The n-hexane, chloroform, n-butanol fractions, and isolated compounds were analyzed by GC-MS, TLC, UPLC ESI MS/MS. Results and discussion: The various chromatographic and spectroscopic results indicate the presence of a different type of phytochemicals like ephedrine, 6hka, vicenin 2 and quercetin 3-sophoroside-7-rhamnoside.

Cyclophilin A is a mitochondrial factor that forms complexes with p23. Correlative evidence for an antiapoptotic action

Cyclophilin A (CyPA) is an abundant and ubiquitously expressed protein belonging to the immunophilin family that has intrinsic peptidyl-prolyl-(cis/trans)-isomerase enzymatic activity. CyPA mediates immunosuppressive action of the cyclic undecapeptide cyclosporine A and is also involved in multiple cellular processes such as protein folding, intracellular trafficking, signal transduction, and transcriptional regulation. CyPA is abundantly expressed in cancer cells, and due to its chaperone nature, its expression is induced upon the onset of stress. In this study, it is demonstrated that a significant pool of this immunophilin is primarily an intramitochondrial factor that migrates to the nucleus when cells are stimulated with stressors. CyPA shows antiapoptotic action per se and the capability of forming ternary complexes with cytochrome c and the small acidic cochaperone p23, the latter interaction being independent of the usual association of p23 with the heat-shock protein of 90-kDa, Hsp90. These CyPA•p23 complexes enhance the antiapoptotic response of the cell, suggesting that both proteins form a functional unit whose high level of expression plays a significant role in cell survival.

Sensitivity of Rodent Microglia to Kynurenines in Models of Epilepsy and Inflammation In Vivo and In Vitro: Microglia Activation Is Inhibited by Kynurenic Acid and the Synthetic Analogue SZR104

Kynurenic acid is an endogenous modulator of ionotropic glutamate receptors and a suppressor of the immune system. Since glutamate and microglia are important in the pathogenesis of epilepsy, we investigated the possible action of the synthetic kynurenic acid analogue, SZR104, in epileptic mice and the action of kynurenic acid and SZR104 on the phagocytotic activity of cultured microglia cells. Pilocarpine epilepsy was used to test the effects of SZR104 on morphological microglia transformation, as evaluated through ionized calcium-binding adaptor molecule 1 (Iba1) immunohistochemistry. Microglia-enriched rat secondary cultures were used to investigate phagocytosis of fluorescent microbeads and Iba1 protein synthesis in control and lipopolysaccharide-challenged cultures. SZR104 inhibited microglia transformation following status epilepticus. Kynurenic acid and SZR104 inhibited lipopolysaccharide-stimulated phagocytotic activity of microglia cells. Although kynurenic acid and its analogues proved to be glutamate receptor antagonists, their immunosuppressive action was dominant in epilepsy. The inhibition of phagocytosis in vitro raised the possibility of the inhibition of genes encoding inflammatory cytokines in microglial cells.

Risk of malignancy and biologic therapy in rheumatic inflammatory diseases: A single-center experience

ObjectivesBiologic disease modifying anti-rheumatic drugs (bDMARDs) have significantly improved the care of patients with rheumatic muscle-skeletal disorders (RMDs). Considering their immunosuppressive action, a theoretical increase of malignancy risk has been a major concern in the last few decades. The objective of this study is to analyze the incidence of malignancies in a cohort of patients affected by rheumatoid arthritis (RA), psoriathic arthritis (PsA), and ankylosing spondylitis (AS) treated with bDMARDs.MethodsThe charts of bDMARD-treated RMD patients were reviewed, and data about bDMARD exposure and malignant cancers (excluding non-melanoma skin cancer) were collected.Results921 patients were included (median age: 50.59 years, 66.67% females); 1374 bDMARD treatments were administered, 87.12% were tumor necrosis factor inhibitors. A total of 21 malignant neoplasms were detected in 21 patients (61.90% females, median age at cancer diagnosis: 64.99 years), 66.67% in RA patients, 19.05% in PsA, and 14.28% in AS. Among them, 10 patients (47.62%) were treated with etanercept, 6 patients (28.57%) with adalimumab, and 1 case each with tocilizumab, certolizumab, golimumab, infliximab, and abatacept. The most common malignancies that we found were lung cancers, ductal mammary carcinomas, melanomas, and lymphomas. The incidence rate (IR) of malignancies in our cohort was 3.47 per 1000 person-years (p-y); the higher IRs were in RA patients (5.13 per 1000 p-y), in males (4.21 per 1000 p-y), and in patients aged >70 years (10.14 per 1000 p-y).ConclusionsThe results of our study showed IR of malignancies in RMD patients treated with bDMARDs that is in agreement with literature data.