The modulatory mechanisms of fenofibrate on human primary T cells

Fenofibrate for COVID-19 and related complications as an approach to improve treatment outcomes: the missed key for Holy Grail

INTRODUCTION

Fenofibrate is an agonist of peroxisome proliferator activated receptor alpha (PPAR-α), that possesses anti-inflammatory, antioxidant, and anti-thrombotic properties. Fenofibrate is effective against a variety of viral infections and different inflammatory disorders. Therefore, the aim of critical review was to overview the potential role of fenofibrate in the pathogenesis of SARS-CoV-2 and related complications.

RESULTS

By destabilizing SARS-CoV-2 spike protein and preventing it from binding angiotensin-converting enzyme 2 (ACE2), a receptor for SARS-CoV-2 entry, fenofibrate can reduce SARS-CoV-2 entry in human cells Fenofibrate also suppresses inflammatory signaling pathways, which decreases SARS-CoV-2 infection-related inflammatory alterations. In conclusion, fenofibrate anti-inflammatory, antioxidant, and antithrombotic capabilities may help to minimize the inflammatory and thrombotic consequences associated with SARSCoV-2 infection. Through attenuating the interaction between SARS-CoV-2 and ACE2, fenofibrate can directly reduce the risk of SARS-CoV-2 infection.

CONCLUSIONS

As a result, fenofibrate could be a potential treatment approach for COVID-19 control.

Neuroinflammation in Schizophrenia: The Key Role of the WNT/β-Catenin Pathway

Schizophrenia is a very complex syndrome involving widespread brain multi-dysconnectivity. Schizophrenia is marked by cognitive, behavioral, and emotional dysregulations. Recent studies suggest that inflammation in the central nervous system (CNS) and immune dysfunction could have a role in the pathogenesis of schizophrenia. This hypothesis is supported by immunogenetic evidence, and a higher incidence rate of autoimmune diseases in patients with schizophrenia. The dysregulation of the WNT/β-catenin pathway is associated with the involvement of neuroinflammation in schizophrenia. Several studies have shown that there is a vicious and positive interplay operating between neuroinflammation and oxidative stress. This interplay is modulated by WNT/β-catenin, which interacts with the NF-kB pathway; inflammatory factors (including IL-6, IL-8, TNF-α); factors of oxidative stress such as glutamate; and dopamine. Neuroinflammation is associated with increased levels of PPARγ. In schizophrenia, the expression of PPAR-γ is increased, whereas the WNT/β-catenin pathway and PPARα are downregulated. This suggests that a metabolic-inflammatory imbalance occurs in this disorder. Thus, this research’s triptych could be a novel therapeutic approach to counteract both neuroinflammation and oxidative stress in schizophrenia.

Epigallocatechin-3-gallate exhibits immunomodulatory effects in human primary T cells

T cells secrete several inflammatory cytokines that play a critical role in the progression of atherosclerosis. Although green tea epigallocatechin-3-gallate (EGCG) exerts anti-inflammatory and anti-atherosclerotic effects in animals, few studies have identified the mechanism underlying these effects in human primary T cells. This study investigated the pathway involved in EGCG modulation of cytokine secretion in activated human primary T cells. We pre-treated human primary T cells with EGCG (0.1, 1, 5, 10, and 20 μM) for 4 h and incubated them with or without phorbol 12-myristate 13-acetate and ionomycin (P/I) for 20 h. The cytokine production, activator protein (AP)-1 binding activity, and level of mitogen-activated protein kinase (MAPK) were assessed using enzyme-linked immunosorbent assay, electrophoretic mobility shift assay, and Western blotting, respectively. At 10 and 20 μM, EGCG decreased interleukin (IL)-2 levels by 26.0% and 38.8%, IL-4 levels by 41.5% and 55.9%, INF-γ levels by 31.3% and 34.7%, and tumor-necrosis factor (TNF)-α levels by 23.0% and 37.6%, respectively. In addition, the level of phosphorylated c-Jun N-terminal (p-JNK) and extracellular signal-regulated kinase (p-ERK) was decreased, but not the level of p-p38 MAPK. EGCG did not alter any of the total protein amounts, suggesting a selective effect on specific types of MAPKs in stimulated human T cells. EGCG tended to inactivate AP-1 DNA-binding activity. The P/I-induced production of IL-2, IL-4, INF-γ, and TNF-α by human T cells was suppressed by AP-1 inhibitor in a concentration-dependent manner. In conclusion, EGCG suppressed cytokine secretion in activated human primary T cells, and this effect was likely mediated by AP-1 inactivation through the ERK and JNK, but not p38 MAPK, pathways. These results may be related to the mechanisms through which EGCG inhibits immune- or inflammation-related atherogenesis.

Fenofibrate ameliorates testicular damage in rats with streptozotocin-induced type 1 diabetes: role of HO-1 and p38 MAPK

BACKGROUND

Since diabetes mellitus type-1 (DM-1) induces testicular oxidative and inflammatory damage with finally an ultimate male infertility, and as fenofibrate (FEN) plays an important antioxidant and anti-inflammatory role, the aim of the present study was to investigate the effects of FEN on diabetes-induced reproductive damage and clarifying the underlying related mechanisms.

METHODS

DM-1 was induced in male Wistar rats by a single intraperitoneal injection of streptozotocin (50 mg/kg). FEN (100 mg/kg/day, orally) was administrated to diabetic rats for 4 weeks. Testicular damage was detected by estimation of both testicular and body weights, assessment of serum testosterone, testicular oxidative stress parameters (malondialdehyde and nitric oxide levels) and testicular oxidant defenses (reduced glutathione, superoxide dismutase and hemeoxygenase-1). Expressions of the inflammatory markers (inducible nitric oxide synthase, p38 mitogen-activated protein kinase (MAPK), tumor necrosis factor alpha, interleukin-6 and apoptotic marker (caspase-3) were evaluated in testicular tissue. Our results were confirmed by histopathological examination of testicular tissues.

RESULTS

Diabetic testicular damage was proved by both biochemical and histopathological examinations. FEN treatment reversed diabetic testicular damage; normalized the serum testosterone level, improved anti-oxidative capacity, ameliorated the pro-inflammatory cytokine expression in testicular tissue with the down regulation of p38 MAPK mediated-testicular apoptosis.

CONCLUSION

FEN treatment exerted a protective effect against streptozotocin-induced diabetic reproductive dysfunction not only through its powerful antioxidant and hypoglycemic effects, but also through its anti-inflammatory and anti-apoptotic effect via down-regulation of testicular p38 MAPK expression in diabetic rats.

Pitavastatin Exerts Potent Anti-Inflammatory and Immunomodulatory Effects via the Suppression of AP-1 Signal Transduction in Human T Cells

Statins inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase are the standard treatment for hypercholesterolemia in atherosclerotic cardiovascular disease (ASCVD), mediated by inflammatory reactions within vessel walls. Several studies highlighted the pleiotropic effects of statins beyond their lipid-lowering properties. However, few studies investigated the effects of statins on T cell activation. This study evaluated the immunomodulatory capacities of three common statins, pitavastatin, atorvastatin, and rosuvastatin, in activated human T cells. The enzyme-linked immunosorbent assay (ELISA) and quantitative real time polymerase chain reaction (qRT-PCR) results demonstrated stronger inhibitory effects of pitavastatin on the cytokine production of T cells activated by phorbol 12-myristate 13-acetate (PMA) plus ionomycin, including interleukin (IL)-2, interferon (IFN)-γ, IL-6, and tumor necrosis factor α (TNF-α). Molecular investigations revealed that pitavastatin reduced both activating protein-1 (AP-1) DNA binding and transcriptional activities. Further exploration showed the selectively inhibitory effect of pitavastatin on the signaling pathways of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK), but not c-Jun N-terminal kinase (JNK). Our findings suggested that pitavastatin might provide additional benefits for treating hypercholesterolemia and ASCVD through its potent immunomodulatory effects on the suppression of ERK/p38/AP-1 signaling in human T cells.

The PPARα agonist fenofibrate attenuates disruption of dopamine function in a maternal immune activation rat model of schizophrenia

Aims

Prenatal maternal immune activation (MIA) is associated with a risk to develop schizophrenia and affects dopamine systems in the ventral tegmental area (VTA), key region in the neurobiology of psychoses. Considering the well‐described sex differences in schizophrenia, we investigated whether sex affects MIA impact on dopamine system and on schizophrenia‐related behavioral phenotype. Furthermore, considering peroxisome proliferator‐activated receptor‐α (PPARα) expression in the CNS as well as its anti‐inflammatory and neuroprotective properties, we tested if PPARα activation by prenatal treatment with a clinically available fibrate (fenofibrate) may mitigate MIA‐related effects.

Methods

We induced MIA in rat dams with polyriboinosinic‐polyribocytidylic acid (Poly I:C) and assessed prepulse inhibition and dopamine neuron activity in the VTA by means of electrophysiological recordings in male and female preweaned and adult offspring.

Results

Poly I:C‐treated males displayed prepulse inhibition deficits, reduced number and firing rate of VTA dopamine neurons, and paired‐pulse facilitation of inhibitory and excitatory synapses. Prenatal fenofibrate administration attenuated detrimental effects induced by MIA on both the schizophrenia‐like behavioral phenotype and dopamine transmission in male offspring.

Conclusion

Our study confirms previous evidence that females are less susceptible to MIA and highlights PPARα as a potential target for treatments in schizophrenia.

Gemfibrozil attenuates the inflammatory response and protects rats from abdominal sepsis

Sepsis is a serious condition characterized by an infectious process that induces a severe systemic inflammatory response. In this study, the effects of gemfibrozil (GFZ) on the inflammatory response associated with abdominal sepsis were investigated using a rat model of cecal-ligation and puncture (CLP). Male Wistar rats were randomly divided into three groups: Sham-operated group (sham), where laparotomy was performed, the intestines were manipulated, and the cecum was ligated but not punctured; control group, subjected to CLP; and GFZ group, which received GFZ prior to undergoing CLP. The groups were then subdivided into three different time-points: 2, 4 and 24 h, indicating the time at which blood samples were obtained for analysis. Serum concentrations of tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), malondialdehyde (MDA), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) were determined. The LDH, AST and ALT values were significantly elevated following CLP compared with those in the sham group, and GFZ treatment was able to reduce these elevations. GFZ also reduced the sepsis-induced elevations of TNF-α and IL-1. In conclusion, GFZ treatment was able to attenuate the inflammatory response associated with CLP-induced sepsis, by diminishing the release of inflammatory cytokines, thereby reducing tissue injury and oxidative stress.

Modulation of both activator protein-1 and nuclear factor-kappa B signal transduction of human T cells by amiodarone

Amiodarone, a common and effective antiarrhythmic drug, has been reported to have anti-inflammatory effects such as reducing the activation and movement of neutrophils. However, its effects on human T cells remain unclear. The aim of this study was to elucidate the effects and possible underlying mechanisms of amiodarone on human T cells. We isolated human primary T cells from the peripheral blood of healthy volunteers and performed enzyme-linked immunosorbent assay (ELISA), flow cytometry, electrophoretic mobility shift assay, luciferase assay, and Western blotting to evaluate the modulatory effects of amiodarone on human T cells. We found that amiodarone dose dependently inhibited the production of cytokines, including interleukin-2 (IL-2), IL-4, tumor necrosis factor-alpha, and interferon-gamma in activated human T cells. By flow cytometry, we demonstrated that amiodarone suppressed the expression of IL-2 receptor-alpha (CD25) and CD69, the cell surface markers of activated T cells. Moreover, molecular investigations revealed that amiodarone down-regulated activator protein-1 (AP-1) and nuclear factor kappa-B (NF-κB) DNA-binding activities in activated human T cells and also inhibited DNA binding and transcriptional activities of both AP-1 and NF-κB in Jurkat cells. Finally, by Western blotting, we showed that amiodarone reduced the activation of c-Jun NH(2)-terminal protein kinase and P38 mitogen-activated protein kinase, and suppressed stimuli-induced I-kappa B-alpha degradation in activated human T cells. Through regulation of AP-1 and NF-κB signaling, amiodarone inhibits cytokine production and T cell activation. These results show the pleiotropic effects of amiodarone on human T cells and suggest its therapeutic potential in inflammation-related cardiovascular disorders.

The synthetic cannabinoid R(+)WIN55,212-2 augments interferon-β expression via peroxisome proliferator-activated receptor-α

We have demonstrated that R(+)WIN55,212-2, a synthetic cannabinoid that possesses cannabimimetic properties, acts as a novel regulator of Toll-like receptor 3 (TLR3) signaling to interferon (IFN) regulatory factor 3 (IRF3) activation and IFN-β expression, and this is critical for manifesting its protective effects in a murine multiple sclerosis model. Here we investigated the role of peroxisome proliferator-activated receptor-α (PPARα) in mediating the effects of R(+)WIN55,212-2 on this pathway. Data herein demonstrate that the TLR3 agonist poly(I:C) promotes IFN-β expression and R(+)WIN55,212-2 enhances TLR3-induced IFN-β expression in a stereoselective manner via PPARα. R(+)WIN55,212-2 promotes increased transactivation and expression of PPARα. Using the PPARα antagonist GW6471, we demonstrate that R(+)WIN55,212-2 acts via PPARα to activate JNK, activator protein-1, and positive regulatory domain IV to transcriptionally regulate the IFN-β promoter. Furthermore, GW6471 ameliorated the protective effects of R(+)WIN55,212-2 during the initial phase of experimental autoimmune encephalomyelitis. Overall, these findings define PPARα as an important mediator in manifesting the effects of R(+)WIN55,212-2 on the signaling cascade regulating IFN-β expression. The study adds to our molecular appreciation of potential therapeutic effects of R(+)WIN55,212-2 in multiple sclerosis.