Superoxide anion mediates the L-selectin down-regulation induced by non-steroidal anti-inflammatory drugs in human neutrophils

Anti-Inflammatory Activity of N'-(3-(1H-indol-3-yl)benzylidene)-2-cyanoacetohydrazide Derivative via sGC-NO/Cytokine Pathway

The N-acylhydrazone function has been reported as a pharmacophore group of molecules with diverse pharmacological activities, including anti-inflammatory effects. Therefore, this study was designed to evaluate the anti-inflammatory potential of the compound N'-(3-(1H-indol-3-yl)benzylidene)-2-cyanoacetohydrazide (JR19) in vivo. The study started with the carrageenan-induced peritonitis model, followed by an investigation of leukocyte migration using the subcutaneous air pouch test and an assessment of the antinociceptive profile using formalin-induced pain. A preliminary molecular docking study focusing on the crystallographic structures of NFκB, iNOS, and sGC was performed to determine the likely mechanism of action. The computational study revealed satisfactory interaction energies with the selected targets, and the same peritonitis model was used to validate the involvement of the nitric oxide pathway and cytokine expression in the peritoneal exudate of mice pretreated with L-NAME or methylene blue. In the peritonitis assay, JR19 (10 and 20 mg/kg) reduced leukocyte migration by 59% and 52%, respectively, compared to the vehicle group, with the 10 mg/kg dose used in subsequent assays. In the subcutaneous air pouch assay, the reduction in cell migration was 66%, and the response to intraplantar formalin was reduced by 39%, particularly during the inflammatory phase, suggesting that the compound lacks central analgesic activity. In addition, a reversal of the anti-inflammatory effect was observed in mice pretreated with L-NAME or methylene blue, indicating the involvement of iNOS and sGC in the anti-inflammatory response of JR19. The compound effectively and significantly decreased the levels of IL-6, TNF-α, IL-17, and IFN-γ, and this effect was reversed in animals pretreated with L-NAME, supporting a NO-dependent anti-inflammatory effect. In contrast, pretreatment with methylene blue only reversed the reduction in TNF-α levels. Therefore, these results demonstrate the pharmacological potential of the novel N-acylhydrazone derivative, which acts through the nitric oxide pathway and cytokine signaling, making it a strong candidate as an anti-inflammatory and immunomodulatory agent.

Polysalicylic Acid Polymer Microparticle Decoys Therapeutically Treat Acute Respiratory Distress Syndrome

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) remain problematic due to high mortality rates and lack of effective treatments. Neutrophilic injury contributes to mortality in ALI/ARDS. Here, technology for rapid ARDS intervention is developed and evaluated, where intravenous salicylic acid-based polymer microparticles, i.e., Poly-Aspirin (Poly-A), interfere with neutrophils in blood, reducing lung neutrophil infiltration and injury in vivo in mouse models of ALI/ARDS. Importantly, Poly-A particles reduce multiple inflammatory cytokines in the airway and bacterial load in the bloodstream in a live bacteria lung infection model of ARDS, drastically improving survival. It is observed that phagocytosis of the Poly-A microparticles, with salicylic acid in the polymer backbone, alters the neutrophil surface expression of adhesion molecules, potentially contributing to their added therapeutic benefits. Given the proven safety profile of the microparticle degradation products-salicylic acid and adipic acid-it is anticipated that the Poly-A particles represent a therapeutic strategy in ARDS with a rare opportunity for rapid clinical translation.

A comprehensive guide to the pharmacologic regulation of angiotensin converting enzyme 2 (ACE2), the SARS-CoV-2 entry receptor

The recent emergence of coronavirus disease-2019 (COVID-19) as a global pandemic has prompted scientists to address an urgent need for defining mechanisms of disease pathology and treatment. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent for COVID-19, employs angiotensin converting enzyme 2 (ACE2) as its primary target for cell surface attachment and likely entry into the host cell. Thus, understanding factors that may regulate the expression and function of ACE2 in the healthy and diseased body is critical for clinical intervention. Over 66% of all adults in the United States are currently using a prescription drug and while earlier findings have focused on possible upregulation of ACE2 expression through the use of renin angiotensin system (RAS) inhibitors, mounting evidence suggests that various other widely administered drugs used in the treatment of hypertension, heart failure, diabetes mellitus, hyperlipidemias, coagulation disorders, and pulmonary disease may also present a varied risk for COVID-19. Specifically, we summarize mechanisms on how heparin, statins, steroids and phytochemicals, besides their established therapeutic effects, may also interfere with SARS-CoV-2 viral entry into cells. We also describe evidence on the effect of several vitamins, phytochemicals, and naturally occurring compounds on ACE2 expression and activity in various tissues and disease models. This comprehensive review aims to provide a timely compendium on the potential impact of commonly prescribed drugs and pharmacologically active compounds on COVID-19 pathology and risk through regulation of ACE2 and RAS signaling.

Aqueous extract of Paullinia cupana attenuates renal and hematological effects associated with ketoprofen

This study aimed to evaluate the effect of aqueous extract of Paullinia cupana (AEG) against ketoprofen side effects, through biochemical, hematological, and histological parameters. AEG showed antioxidant activity in the DPPH^• scavenging (IC₅₀  = 17.00 ± 1.00 µg/ml) and HPLC analysis revealed that this extract is constituted by antioxidants (caffeine, catechins, theobromine, and polyphenols). In vivo experiments in female Wistar rats demonstrated that alterations in urea, creatinine, and uric acid levels promoted (p < .05) by ketoprofen were reversed when AEG was co-administered. Ketoprofen significantly decreased the catalase levels of animal tissues (p < .05), which were restored when AEG was co-administered with the mentioned drug. Histological analysis showed that AEG protected tissues from damages caused by ketoprofen. Moreover, AEG reestablished the number of white blood cells, which had decreased when ketoprofen was administered. In conclusion, this study suggested that the association between ketoprofen and AEG may be an alternative to reduce health damages caused by this drug. PRACTICAL APPLICATIONS: Paullinia cupana, popularly known as guaraná, is commonly consumed as a beverage in Brazil and exhibits pharmacological and beneficial effects to humans. Ketoprofen is an efficacious drug employed in the treatment of inflammatory processes. However, this drug can cause several side effects in humans. Thus, the usage of natural products and plant extracts that can reduce such undesirable effects consists in a valuable strategy to be applied in therapeutic interventions.

Diclofenac impairs autophagic flux via oxidative stress and lysosomal dysfunction: Implications for hepatotoxicity

Treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with various side effects, including cardiovascular and hepatic disorders. Studies suggest that mitochondrial damage and oxidative stress are important mediators of toxicity, yet the underlying mechanisms are poorly understood. In this study, we identified that some NSAIDs, including diclofenac, inhibit autophagic flux in hepatocytes. Further detailed studies demonstrated that diclofenac induced a reactive oxygen species (ROS)-dependent increase in lysosomal pH, attenuated cathepsin activity and blocked autophagosome-lysosome fusion. The reactivation of lysosomal function by treatment with clioquinol or transfection with the transcription factor EB restored lysosomal pH and thus autophagic flux. The production of mitochondrial ROS is critical for this process since scavenging ROS reversed lysosomal dysfunction and activated autophagic flux. The compromised lysosomal activity induced by diclofenac also inhibited the fusion with and degradation of mitochondria by mitophagy. Diclofenac-induced cell death and hepatotoxicity were effectively protected by rapamycin. Thus, we demonstrated that diclofenac induces the intracellular ROS production and lysosomal dysfunction that lead to the suppression of autophagy. Impaired autophagy fails to maintain mitochondrial integrity and aggravates the cellular ROS burden, which leads to diclofenac-induced hepatotoxicity.

L-selectin expression is regulated by CXCL8-induced reactive oxygen species produced during human neutrophil rolling

Neutrophils destroy invading microorganisms by phagocytosis by bringing them into contact with bactericidal substances, among which ROS are the most important. However, ROS also function as important physiological regulators of cellular signaling pathways. Here, we addressed the involvement of oxygen derivatives in the regulation of human neutrophil rolling, an essential component of the inflammatory response. Flow experiments using dihydroethidium-preloaded human neutrophils showed that these cells initiate an early production of intracellular ROS during the rolling phase of the adhesion cascade, a phenomenon that required cell rolling, and the interaction of the chemokine receptor CXCR2 with their ligand CXCL8. Flow cytometry experiments demonstrated that L-selectin shedding in neutrophils is triggered by ROS through an autocrine-paracrine mechanism. Preincubation of neutrophils with the NADPH oxidase complex inhibitor diphenyleniodonium chloride significantly increased the number of rolling neutrophils on endothelial cells. Interestingly, the same effect was observed when CXCL8 signaling was interfered using either a blocking monoclonal antibody or an inhibitor of its receptor. These findings indicate that, in response to CXCL8, neutrophils initiate ROS production during the rolling phase of the inflammatory response. This very early ROS production might participate in the modulation of the inflammatory response by inducing L-selectin shedding in neutrophils.

A head-to-tail view of L-selectin and its impact on neutrophil behaviour

L-selectin is a type I transmembrane cell adhesion molecule expressed on most circulating leukocytes, including neutrophils. Engagement of L-selectin with endothelial-derived ligands initiates neutrophil tethering and rolling behaviour along luminal walls of post-capillary venules, constituting the first step of the multi-step adhesion cascade. There is a large body of evidence to suggest that signalling downstream of L-selectin can influence neutrophil behaviour: adhesion, migration and priming. This review will cover aspects of L-selectin form and function and introduce the “triad of L-selectin regulation”, highlighting the inextricable links between adhesion, signalling and ectodomain shedding and also highlighting the cytosolic proteins that interconnect them. Recent advances in how L-selectin impacts priming, transendothelial migration (TEM) and cell polarity will also be discussed.

NSAIDs: learning new tricks from old drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs) comprise a heterogeneous group of pharmacological agents used for the symptomatic treatment of fever, pain, and inflammation. Although the main mechanism of action of NSAIDs consists of inhibiting prostaglandin synthesis by blocking the enzyme cyclooxygenase (COX), clinical, and experimental data strongly indicate the existence of additional mechanisms. Some of the COX-independent effects are related to the ability of NSAIDs to penetrate biological membranes and disrupt important molecular interactions necessary for a wide array of cellular functions, including cell adhesion. These effects, in particular those that interfere with L-selectin function in neutrophils during the inflammatory response, may contribute to the anti-inflammatory properties that NSAIDs exert in vivo. Recent contributions in this field have shown that the anti-L-selectin effect of NSAIDs is related to the NADPH-oxidase-dependent generation of superoxide anion at the plasma membrane. These findings might represent a novel approach for developing new and effective anti-inflammatory compounds with a better safety profile than the currently available NSAIDs.

The mitochondrial protein TCAIM regulates activation of T cells and thereby promotes tolerance induction of allogeneic transplants

Primary T cell activation and effector cell differentiation is required for rejection of allogeneic grafts in naïve recipients. It has become evident, that mitochondria play an important role for T cell activation. Expression of several mitochondrial proteins such as TCAIM (T cell activation inhibitor, mitochondrial) is down-regulated upon T cell receptor triggering. Here we report that TCAIM inhibited spontaneous development of memory and effector T cells. CD4(+) T cells from Tcaim knock-in (KI) mice showed reduced activation, cytokine secretion and proliferation in vitro. Tcaim KI T cells tolerated allogeneic skin grafts upon transfer into Rag-1 KO mice. CD4(+) and CD8(+) T cells from these mice did not infiltrate skin grafts and kept a naïve or central memory phenotype, respectively. They were unable to acquire effector phenotype and functions. TCAIM altered T cell activation-induced mitochondrial distribution and reduced mitochondrial reactive oxygen species (mROS) production. Thus, TCAIM controls T cell activation and promotes tolerance induction probably by regulating TCR-mediated mitochondrial distribution and mROS production.

The Multifaceted Roles Neutrophils Play in the Tumor Microenvironment

Neutrophils are myeloid cells that constitute 50-70 % of all white blood cells in the human circulation. Traditionally, neutrophils are viewed as the first line of defense against infections and as a major component of the inflammatory process. In addition, accumulating evidence suggest that neutrophils may also play a key role in multiple aspects of cancer biology. The possible involvement of neutrophils in cancer prevention and promotion was already suggested more than half a century ago, however, despite being the major component of the immune system, their contribution has often been overshadowed by other immune components such as lymphocytes and macrophages. Neutrophils seem to have conflicting functions in cancer and can be classified into anti-tumor (N1) and pro-tumor (N2) sub-populations. The aim of this review is to discuss the varying nature of neutrophil function in the cancer microenvironment with a specific emphasis on the mechanisms that regulate neutrophil mobilization, recruitment and activation.