Mechanisms Underlying Neuroprotection by the NSAID Mefenamic Acid in an Experimental Model of Stroke

Antiseizure properties of fenamate NSAIDs determined in mature human stem-cell derived neuroglial circuits

Repeated and uncontrolled seizures in epilepsy result in brain cell loss and neural inflammation. Current anticonvulsants primarily target ion channels and receptors implicated in seizure activity. Identification of neurotherapeutics that can inhibit epileptiform activity and reduce inflammation in the brain may offer significant benefits in the long-term management of epilepsy. Fenamates are unique because they are both non-steroidal anti-inflammatory drugs (NSAIDs) and highly subunit selective modulators of GABAA receptors. In the current study we have investigated the hypothesis that fenamates have antiseizure properties using mature human stem cell-derived neuro-glia cell cultures, maintained in long-term culture, and previously shown to be sensitive to first, second and third generation antiepileptics. Mefenamic acid, flufenamic acid, meclofenamic acid, niflumic acid, and tolfenamic acid (each tested at 10-100 μM) attenuated 4-aminopyridine (4-AP, 100 μM) evoked epileptiform activity in a dose-dependent fashion. These actions were as effective diazepam (3-30 μM) and up to 200 times more potent than phenobarbital (300-1,000 μM). The low (micromolar) concentrations of fenamates that inhibited 4-AP evoked epileptiform activity correspond to those reported to potentiate GABAA receptor function. In contrast, the fenamates had no effect on neural spike amplitudes, indicating that their antiseizure actions did not result from inhibition of sodium-channels. The antiseizure actions of fenamates were also not replicated by either of the two non-fenamate NSAIDs, ibuprofen (10-100 μM) or indomethacin (10-100 μM), indicating that inhibition of cyclooxygenases is not the mechanism through which fenamates have anticonvulsant properties. This study therefore shows for the first time, using functionally mature human stem cell-derived neuroglial circuits, that fenamate NSAIDs have powerful antiseizure actions independent of, and in addition to their well-established anti-inflammatory properties, suggesting these drugs may provide a novel insight and new approach to the treatment of epilepsy in the future.

Mitochondrial protective effects caused by the administration of mefenamic acid in sepsis

The pathophysiology of sepsis may involve the activation of the NOD-type receptor containing the pyrin-3 domain (NLPR-3), mitochondrial and oxidative damages. One of the primary essential oxidation products is 8-oxoguanine (8-oxoG), and its accumulation in mitochondrial DNA (mtDNA) induces cell dysfunction and death, leading to the hypothesis that mtDNA integrity is crucial for maintaining neuronal function during sepsis. In sepsis, the modulation of NLRP-3 activation is critical, and mefenamic acid (MFA) is a potent drug that can reduce inflammasome activity, attenuating the acute cerebral inflammatory process. Thus, this study aimed to evaluate the administration of MFA and its implications for the reduction of inflammatory parameters and mitochondrial damage in animals submitted to polymicrobial sepsis. To test our hypothesis, adult male Wistar rats were submitted to the cecal ligation and perforation (CLP) model for sepsis induction and after receiving an injection of MFA (doses of 10, 30, and 50 mg/kg) or sterile saline (1 mL/kg). At 24 h after sepsis induction, the frontal cortex and hippocampus were dissected to analyze the levels of TNF-α, IL-1β, and IL-18; oxidative damage (thiobarbituric acid reactive substances (TBARS), carbonyl, and DCF-DA (oxidative parameters); protein expression (mitochondrial transcription factor A (TFAM), NLRP-3, 8-oxoG; Bax, Bcl-2 and (ionized calcium-binding adaptor molecule 1 (IBA-1)); and the activity of mitochondrial respiratory chain complexes. It was observed that the septic group in both structures studied showed an increase in proinflammatory cytokines mediated by increased activity in NLRP-3, with more significant oxidative damage and higher production of reactive oxygen species (ROS) by mitochondria. Damage to mtDNA it was also observed with an increase in 8-oxoG levels and lower levels of TFAM and NGF-1. In addition, this group had an increase in pro-apoptotic proteins and IBA-1 positive cells. However, MFA at doses of 30 and 50 mg/kg decreased inflammasome activity, reduced levels of cytokines and oxidative damage, increased bioenergetic efficacy and reduced production of ROS and 8-oxoG, and increased levels of TFAM, NGF-1, Bcl-2, reducing microglial activation. As a result, it is suggested that MFA induces protection in the central nervous system early after the onset of sepsis.

Interpreting the Benefit and Risk Data in Between-Drug Comparisons: Illustration of the Challenges Using the Example of Mefenamic Acid versus Ibuprofen

Evidence-based pain therapy should rely on precisely defined and personalized criteria. This includes balancing the benefits and risks not only of single drugs but often requires complex between-drug comparisons. Non-steroidal anti-inflammatory drugs (NSAIDs) have been available for several decades and their use is described in an abundance of guidelines. Most of these guidelines recommend that ‘the selection of a particular NSAID should be based on the benefit-risk balance for each patient’. However, head-to-head studies are often lacking or of poor quality, reflecting the lower standards for clinical research and regulatory approval at the time. The inconsistency of approved indications between countries due to national applications adds to the complexity. Finally, a fading research interest once drugs become generic points to a general deficit in the post-marketing evaluation of medicines. Far from claiming completeness, this narrative review aimed to illustrate the challenges that physicians encounter when trying to balance benefits and risks in a situation of incomplete and inconsistent data on longstanding treatment concepts. Ibuprofen and mefenamic acid, the most frequently sold NSAIDs in Austria, serve as examples. The illustrated principles are, however, not specific to these drugs and are generalizable to any comparison of older drugs in daily clinical practice.

Therapeutic Strategies for Immune Transformation in Parkinson’s Disease

Dysregulation of innate and adaptive immunity can lead to alpha-synuclein (α-syn) misfolding, aggregation, and post-translational modifications in Parkinson’s disease (PD). This process is driven by neuroinflammation and oxidative stress, which can contribute to the release of neurotoxic oligomers that facilitate dopaminergic neurodegeneration. Strategies that promote vaccines and antibodies target the clearance of misfolded, modified α-syn, while gene therapy approaches propose to deliver intracellular single chain nanobodies to mitigate α-syn misfolding, or to deliver neurotrophic factors that support neuronal viability in an otherwise neurotoxic environment. Additionally, transformative immune responses provide potential targets for PD therapeutics. Anti-inflammatory drugs represent one strategy that principally affects innate immunity. Considerable research efforts have focused on transforming the balance of pro-inflammatory effector T cells (Teffs) to favor regulatory T cell (Treg) activity, which aims to attenuate neuroinflammation and support reparative and neurotrophic homeostasis. This approach serves to control innate microglial neurotoxic activities and may facilitate clearance of α-syn aggregates accordingly. More recently, changes in the intestinal microbiome have been shown to alter the gut-immune-brain axis leading to suppressed leakage of bacterial products that can promote peripheral inflammation and α-syn misfolding. Together, each of the approaches serves to interdict chronic inflammation associated with disordered immunity and neurodegeneration. Herein, we examine research strategies aimed at improving clinical outcomes in PD.

Application of ionic liquid to enhance the nose-to-brain delivery of etodolac

The purpose of this study was to enhance the delivery of Etodolac (ETD) to the brain through intranasal administration using an ionic liquid (IL) consisting of ETD and proline ethyl ester. The IL of ETD was prepared by mixing ETD with proline ethyl ester as a counterion in a molar ratio of 1:2.The formation of the IL was confirmed by differential scanning calorimetry (DSC), infrared spectroscopy (IR) and proton nuclear magnetic resonance (¹H-NMR).The solubility of ETD in simulated nasal fluids was improved by approximately 200-fold due to the formation of IL. The intranasal administration of ETD-containing IL, which is viscous, increased the nose-to-brain delivery by approximately 7-fold 30 min after an administration of the ETD solution alone. The enhancement of ETD delivery to the brain from the nose was attributed to the enhanced retention of ETD in the nasal mucosal surface due to the viscosity of IL. The induction of prostaglandin E2 in the brain inflammation that was induced by lipopolysaccharides was significantly suppressed by up to 40% in the IL-treated group compared with the drug-untreated group. Therefore, ETD-containing IL were suggested to be useful in designing intranasal formulations for the nasal delivery of ETDs to the brain.

Flufenamic acid improves survival and neurologic outcome after successful cardiopulmonary resuscitation in mice

Background

Brain injury is the main cause of high mortality and disability after successful cardiopulmonary resuscitation (CPR) from sudden cardiac arrest (CA). The transient receptor potential M4 (TRPM4) channel is a novel target for ameliorating blood–brain barrier (BBB) disruption and neuroinflammation. Herein, we tested whether flufenamic acid (FFA), which is reported to block TRPM4 with high potency, could confer neuroprotection against brain injury secondary to CA/CPR and whether its action was exerted by blocking the TRPM4 channel.

Methods

Wild-type (WT) and Trpm4 knockout (Trpm4^−/−) mice subjected to 10-min CA/CPR were randomized to receive FFA or vehicle once daily. Post-CA/CPR brain injuries including neurologic deficits, survival rate, histological damage, edema formation, BBB destabilization and neuroinflammation were assessed.

Results

In WT mice subjected to CA/CPR, FFA was effective in improving survival and neurologic outcome, reducing neuropathological injuries, attenuating brain edema, lessening the leakage of IgG and Evans blue dye, restoring tight junction protein expression and promoting microglia/macrophages from the pro-inflammatory subtype toward the anti-inflammatory subtype. In comparison to WT mice, Trpm4^−/− mice exhibited less neurologic deficiency, milder histological impairment, more BBB integrity and more anti-inflammatory microglia/macrophage polarization. As expected, FFA did not provide a benefit of superposition compared with vehicle in the Trpm4^−/− mice after CA/CPR.

Conclusions

FFA mitigates BBB breach and modifies the functional status of microglia/macrophages, thereby improving survival and neurologic deficits following CA/CPR. The neuroprotective effects occur at least partially by interfering with the TRPM4 channel in the neurovascular unit. These results indicate the significant clinical potential of FFA to improve the prognosis for CA victims who are successfully resuscitated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02571-2.

Immune Modulatory Effects of Nonsteroidal Anti-inflammatory Drugs in the Perioperative Period and Their Consequence on Postoperative Outcome

Nonsteroidal anti-inflammatory drugs are among the most commonly administered drugs in the perioperative period due to their prominent role in pain management. However, they potentially have perioperative consequences due to immune-modulating effects through the inhibition of prostanoid synthesis, thereby affecting the levels of various cytokines. These effects may have a direct impact on the postoperative outcome of patients since the immune system aims to restore homeostasis and plays an indispensable role in regeneration and repair. By affecting the immune response, consequences can be expected on various organ systems. This narrative review aims to highlight these potential immune system-related consequences, which include systemic inflammatory response syndrome, acute respiratory distress syndrome, immediate and persistent postoperative pain, effects on oncological and neurologic outcome, and wound, anastomotic, and bone healing.

Acteoside isolated from Colebrookea oppositifolia attenuates I/R brain injury in Wistar rats via modulation of HIF-1α, NF-κB, and VEGF pathways

AIMS

The objective of this study was to assess the anti-stroke activity of acteoside isolated from methanolic root extract of C. oppositifolia METHODS: Ischemia-reperfusion(I/R) brain injury was induced in Wistar rats to assess the anti-stroke activity of acteoside. Rats were pretreated with acteoside (10, 25 & 50 mg/kg, p.o.) before the induction of I/R injury. Parameters such as neurological, motor-cognitive functions were evaluated along with morphological (brain volume, infarct size), biochemical (SOD, Catalase, GSH, lipid peroxidation, TNF-α, IL-6, IL-10, ICAM-1, HIF-1α, VEGF, and NF-κB), histopathological, and gene expression studies (HIF-1α, VEGF) were performed to study the protective effect of acteoside against I/R induced brain injury.

RESULTS

I/R injury caused significant deterioration of neurological (p < 0.01), motor (p < 0.01) and cognitive (p < 0.01) functions, associated with increase in the brain volume (p < 0.01), and infarct size (p < 0.01); increase in the levels of MDA, TNF-α, IL-6, ICAM-1, HIF-1α, VEGF, and NF-κB along with significant decrease in SOD, catalase, GSH, and IL-10 (p < 0.01 for all parameters) compared to Sham control group. Histology of brain tissue of disease control group exhibited significant vascular changes, neutrophil infiltration, cerebral oedema, and necrosis of the neuronal cells. Further, the gene-expression studies showed significant increase in the HIF-1α (p < 0.01) and VEGF (p < 0.01) mRNA levels in the I/R control compared to Sham control. Interestingly, the acteoside (10, 25 & 50 mg/kg) has prevented the neurological, motor and cognitive dysfunctions, along with inhibiting the morphological, biochemical, histological and gene expression changes induced by I/R-injury (p < 0.05 for 10 mg; p < 0.01 for 25 & 50 mg/kg of acteoside for all the parameters).

CONCLUSION

These findings suggest that acteoside possess potent anti-stroke activity through modulation of HIF-1α, NF-κB, and VEGF pathway along with its potent antioxidant activity.

Fenamates as Potential Therapeutics for Neurodegenerative Disorders

Neurodegenerative disorders are desperately lacking treatment options. It is imperative that drug repurposing be considered in the fight against neurodegenerative diseases. Fenamates have been studied for efficacy in treating several neurodegenerative diseases. The purpose of this review is to comprehensively present the past and current research on fenamates in the context of neurodegenerative diseases with a special emphasis on tolfenamic acid and Alzheimer's disease. Furthermore, this review discusses the major molecular pathways modulated by fenamates.

Potential Drug Candidates to Treat TRPC6 Channel Deficiencies in the Pathophysiology of Alzheimer's Disease and Brain Ischemia

Alzheimer’s disease and cerebral ischemia are among the many causative neurodegenerative diseases that lead to disabilities in the middle-aged and elderly population. There are no effective disease-preventing therapies for these pathologies. Recent in vitro and in vivo studies have revealed the TRPC6 channel to be a promising molecular target for the development of neuroprotective agents. TRPC6 channel is a non-selective cation plasma membrane channel that is permeable to Ca²⁺. Its Ca²⁺-dependent pharmacological effect is associated with the stabilization and protection of excitatory synapses. Downregulation as well as upregulation of TRPC6 channel functions have been observed in Alzheimer’s disease and brain ischemia models. Thus, in order to protect neurons from Alzheimer’s disease and cerebral ischemia, proper TRPC6 channels modulators have to be used. TRPC6 channels modulators are an emerging research field. New chemical structures modulating the activity of TRPC6 channels are being currently discovered. The recent publication of the cryo-EM structure of TRPC6 channels should speed up the discovery process even more. This review summarizes the currently available information about potential drug candidates that may be used as basic structures to develop selective, highly potent TRPC6 channel modulators to treat neurodegenerative disorders, such as Alzheimer’s disease and cerebral ischemia.

Gadolinium-Based Neuroprognostic Magnetic Resonance Imaging Agents Suppress COX-2 for Prevention of Reperfusion Injury after Stroke

Advancements in recanalization therapies have rendered reperfusion injury an important challenge for stroke management. It is essential to work toward effective therapeutics that protect the ischemic brain from reperfusion injury. Here, we report a new concept of neuroprognostic agents, which combine molecular diagnostic imaging and targeted neuroprotection for treatment of reperfusion injury after stroke. These neuroprognostic agents are inflammation-targeted gadolinium compounds conjugated with nonsteroidal anti-inflammatory drugs (NSAIDs). Our results demonstrated that gadolinium-based MRI contrast agents conjugated with NSAIDs suppressed the increase in cyclooxygenase-2 (COX-2) levels, ameliorated glial activation, and neuron damage that are phenotypic for stroke by mitigating neuroinflammation, which prevented reperfusion injury. In addition, this study showed that the neuroprognostic agents are promising T₁ molecular MRI contrast agents for detecting precise reperfusion injury locations at the molecular level. Our results build on this new concept of neuroprognostics as a novel management strategy for ischemia-reperfusion injury, combining neuroprotection and molecular diagnostics.

Peripheral-to-central immune communication at the area postrema glial-barrier following bleomycin-induced sterile lung injury in adult rats

The pathways for peripheral-to-central immune communication (P → C I-comm) following sterile lung injury (SLI) are unknown. SLI evokes systemic and central inflammation, which alters central respiratory control and viscerosensory transmission in the nucleus tractus solitarii (nTS). These functional changes coincide with increased interleukin-1 beta (IL-1β) in the area postrema, a sensory circumventricular organ that connects P → C I-comm to brainstem circuits that control homeostasis. We hypothesize that IL-1β and its downstream transcriptional target, cyclooxygenase-2 (COX-2), mediate P → C I-comm in the nTS. In a rodent model of SLI induced by intratracheal bleomycin (Bleo), the sigh frequency and duration of post-sigh apnea increased in Bleo- compared to saline- treated rats one week after injury. This SLI-dependent change in respiratory control occurred concurrently with augmented IL-1β and COX-2 immunoreactivity (IR) in the funiculus separans (FS), a barrier between the AP and the brainstem. At this barrier, increases in IL-1β and COX-2 IR were confined to processes that stained for glial fibrillary acidic protein (GFAP) and that projected basolaterally to the nTS. Further, FS radial-glia did not express TNF-α or IL-6 following SLI. To test our hypothesis, we blocked central COX-1/2 activity by intracerebroventricular (ICV) infusion of Indomethacin (Ind). Continuous ICV Ind treatment prevented Bleo-dependent increases in GFAP + and IL-1β + IR, and restored characteristics of sighs that reset the rhythm. These data indicate that changes in sighs following SLI depend partially on activation of a central COX-dependent P → C I-comm via radial-glia of the FS.

Mefenamic acid can attenuate depressive symptoms by suppressing microglia activation induced upon chronic stress

BACKGROUND

Depression is the most debilitating neuropsychiatric disorder, and psychosocial stressors are major risk factors for the onset of depression. Depression is closely associated with chronic inflammation and microglia are the principal mediators of inflammation in the central nervous system (CNS). Mefenamic acid (MA) and celecoxib are nonselective and selective inhibitors of cyclooxygenase (COX), respectively. COX is a key enzyme in mediating inflammatory response in microglia. In this study, we examine the effects of inhibiting COX by MA on depressive-like behaviors and microglia activation in the hippocampus.

METHODS

We evaluate the effect of MA on chronic mild stress (CMS) induced depressive-like behavior by sucrose preference and forced swimming tests. Effect of MA on microglia activation in dentate gyrus (DG) of hippocampus was examined by immunohistochemistry. In vitro experiments including western blotting and phagocytosis assay were used to investigate the effect of MA on microglia activation.

RESULTS

Behavioral assays reveal MA and celecoxib ameliorate CMS-induced depressive-like behavior. Compared to the stressed mice, the number of activated/phagocytic microglia (Iba1⁺/CD68⁺) in DG of hippocampus significantly decreases in stressed mice treated with MA or celecoxib. MA and celecoxib play a role in inhibiting microglia activation by inhibiting of ERK1/2 and P38 MAPK activation and iNOS expression. MA or celecoxib also reduce the high phagocytic activity of activated microglia.

CONCLUSION

MA inhibits microglia activation/phagocytosis induced upon chronic stress in the hippocampus, which might result in the improvement of depressive symptoms.