Pirfenidone Attenuates Microglial Reactivity and Reduces Inducible Nitric Oxide Synthase mRNA Expression After Kainic Acid-Mediated Excitotoxicity in Pubescent Rat Hippocampus

TGF-β as a Key Modulator of Astrocyte Reactivity: Disease Relevance and Therapeutic Implications

Astrocytes are essential for normal brain development and functioning. They respond to brain injury and disease through a process referred to as reactive astrogliosis, where the reactivity is highly heterogenous and context-dependent. Reactive astrocytes are active contributors to brain pathology and can exert beneficial, detrimental, or mixed effects following brain insults. Transforming growth factor-β (TGF-β) has been identified as one of the key factors regulating astrocyte reactivity. The genetic and pharmacological manipulation of the TGF-β signaling pathway in animal models of central nervous system (CNS) injury and disease alters pathological and functional outcomes. This review aims to provide recent understanding regarding astrocyte reactivity and TGF-β signaling in brain injury, aging, and neurodegeneration. Further, it explores how TGF-β signaling modulates astrocyte reactivity and function in the context of CNS disease and injury.

Involvement of H2 S, NO and BDNF-TrkB signalling pathway in the protective effects of simvastatin against pentylenetetrazole-induced kindling and cognitive impairments in mice

Cognitive dysfunction was observed in pentylenetetrazole (PTZ)-kindled mice. The potential effectiveness of simvastatin (SIM) on PTZ-induced kindling and cognitive impairments in mice was evaluated. The influence of SIM on hydrogen sulphide (H2 S), nitric oxide (NO), reactive aldehydes and brain-derived neurotrophic factor/tyrosine receptor kinase B (BDNF-TrkB) signalling was also investigated. Kindling and cognitive impairments in mice were induced by 12 ip injections of PTZ (35 mg/kg) once every alternate day. The levels of reactive aldehydes and nitrite were increased while H2 S was decreased in PTZ-treated mice. These results were accompanied by a reduction in the gene expression of aldehyde dehydrogenase 2, cystathionine β-synthase, BDNF and TrkB. In PTZ-kindled mice, a rise in brain inducible nitric oxide synthase protein expression associated with histopathological changes was observed. SIM administration (1, 5 and 10 mg/kg, daily orally) along with alternate day of PTZ (35 mg/kg) resulted in a decrease in PTZ-induced kindling with a dose-dependent improvement in cognitive function. SIM (10 mg/kg) prevented, to variable extent, the disturbances associated with PTZ-kindled mice with cortical, cerebellar and hippocampal structural improvement. These results suggested that SIM triggers multiple mechanisms that improve cognitive function in PTZ-kindled mice through modulation of oxidative stress, H2 S, NO and BDNF-TrkB signalling pathway.

Pirfenidone alleviates lung ischemia-reperfusion injury in a rat model

OBJECTIVE

Lung ischemia-reperfusion injury is among the complications seen after lung transplantation, resulting in morbidity and mortality. Pirfenidone, an antifibrotic agent for the treatment of idiopathic pulmonary fibrosis, is reported to have cytoprotective properties in various disease models. The purpose of this study was to investigate the effect of pirfenidone on lung ischemia-reperfusion injury.

METHODS

Male Lewis rats (260-290 g) were divided into 3 groups: sham group (n = 5), warm ischemia (WI) group (n = 10), and WI plus pirfenidone (WI+PFD) group (n = 10). The sham group underwent 210 minutes of perfusion without ischemia. The WI and WI+PFD groups underwent 90 minutes of warm ischemia and 120 minutes of reperfusion. In the WI+PFD group, pirfenidone (300 mg/kg) was administered orally by gavage 30 minutes before ischemia. After reperfusion, arterial blood gas analysis, lung mechanics, lung wet-to-dry weight ratio, and histologic findings were obtained. The gene expressions of proinflammatory cytokines in lung tissue were measured by quantitative reverse transcription polymerase chain reaction.

RESULTS

Compared with the WI group, the WI+PFD group had significantly better dynamic pulmonary compliance (P < .01) and oxygenation levels (P < .05). The wet-to-dry ratio was lower in the WI+PFD group (P < .05). Histologic analysis showed that the WI+PFD group had reduced perivascular edema and neutrophil infiltration. The expression of tumor necrosis factor-α messenger RNA was decreased in the WI+PFD group (P < .05).

CONCLUSIONS

Our results revealed that in a rat hilar clamp model, pirfenidone alleviated lung ischemia-reperfusion through anti-inflammatory effects.

Effect of pirfenidone on gastric emptying in a rat model

INTRODUCTION

Gastrointestinal (GI) adverse events (AEs) are commonly reported in patients with idiopathic pulmonary fibrosis who are treated with pirfenidone. Taking pirfenidone with a substantial amount of food or dividing the dose over the course of a meal has been reported to reduce the frequency of GI AEs in clinical practice. In humans, the maximum plasma concentration (C_max) of pirfenidone was reduced when the drug was taken with food compared with the fasting state, and the lower C_max was associated with a reduction in GI AE rates. In this study, the effects of the divided-dose approach and timing of pirfenidone administration relative to meal intake on gastric emptying were assessed using a rat model. The aim of this study was to investigate whether modification of dosing regimens could minimize pirfenidone's effect on inhibition of gastric emptying.

METHODS

Gastric emptying was assessed in male Sprague-Dawley rats after administration of a test meal by weighing stomach contents at various time points up to 120 min after the meal. Pirfenidone was administered via oral gavage either as a single-bolus dose of 30 mg/kg or as divided doses of 3 × 10 mg/kg at intervals ranging from 10 to 30 min for a total duration of 30 to 90 min. In addition, the test meal was given either at 30 min before, coincident with, or 30 min following pirfenidone oral administration.

RESULTS

Administration of an oral 30-mg/kg single-bolus dose of pirfenidone with a meal resulted in a statistically significant decrease in gastric emptying in a rat model. The effect of pirfenidone on decreasing gastric emptying was lessened when the same total dose (i.e., 30 mg/kg) was administered as 3 divided doses (i.e., 3 × 10 mg/kg) over intervals up to 30 min in between each divided dose. Pharmacokinetic simulation suggested that a divided-dosing regimen would decrease pirfenidone C_max relative to single-bolus administration. When the same single-bolus dose of 30 mg/kg was administered 30 min following a meal rather than coincident with a meal, pirfenidone's effect on decreasing gastric emptying was reduced to the same extent as when the dose was divided as 3 × 10 mg/kg over a 90-min period.

CONCLUSIONS

Administration of pirfenidone 30 min after a meal as a single-bolus dose or a divided dose over a 90-min period blunted pirfenidone's effect on inhibition of gastric emptying in rats compared with pirfenidone administration as a single-bolus dose coincident with a meal. Decreased gastric emptying, which is associated with pirfenidone administration, may be one of the contributing factors leading to GI tolerability issues associated with pirfenidone use in humans. Modification of the dosing regimen diminished this impact and may provide insight into possible mitigation strategies to minimize GI-related toxicities in the clinic.

The Endocannabinoid Reuptake Inhibitor WOBE437 Is Orally Bioavailable and Exerts Indirect Polypharmacological Effects via Different Endocannabinoid Receptors

Different anandamide (AEA) transport inhibitors show antinociceptive and antiinflammatory effects in vivo, but due to their concomitant inhibition of fatty acid amide hydrolase (FAAH) and overall poor bioavailability, they cannot be used unequivocally to study the particular role of endocannabinoid (EC) transport in pathophysiological conditions in vivo. Here, the potent and selective endocannabinoid reuptake inhibitor WOBE437, which inhibits AEA and 2-arachidonoylglycerol (2-AG) transport, was tested for its oral bioavailability to the brain. WOBE437 is assumed to locally increase EC levels in tissues in which facilitated EC reuptake intermediates subsequent hydrolysis. Given the marked polypharmacology of ECs, we hypothesized to see differential effects on distinct EC receptors in animal models of acute and chronic pain/inflammation. In C57BL6/J male mice, WOBE437 was orally bioavailable with an estimated t_max value of ≤20 min in plasma (C_max ∼ 2000 pmol/mL after 50 mg/kg, p.o.) and brain (C_max ∼ 500 pmol/g after 50 mg/kg, p.o.). WOBE437 was cleared from the brain after approximately 180 min. In addition, in BALB/c male mice, acute oral administration of WOBE437 (50 mg/kg) exhibited similar brain concentrations after 60 min and inhibited analgesia in the hot plate test in a cannabinoid CB1 receptor-dependent manner, without inducing catalepsy or affecting locomotion. WOBE437 significantly elevated AEA in the somatosensory cortex, while showing dose-dependent biphasic effects on 2-AG levels in plasma but no significant changes in N-acylethanolamines other than AEA in any of the tissues. In order to explore the presumed polypharmacology mediated via elevated EC levels, we tested this EC reuptake inhibitor in complete Freud's adjuvant induced monoarthritis in BALB/c mice as a model of chronic inflammation. Repetitive doses of WOBE437 (10 mg/kg, i.p.) attenuated allodynia and edema via cannabinoid CB2, CB1, and PPARγ receptors. The allodynia inhibition of WOBE437 treatment for 3 days was fully reversed by antagonists of any of the receptors. In the single dose treatment the CB2 and TRPV1 antagonists significantly blocked the effect of WOBE437. Overall, our results show the broad utility of WOBE437 for animal experimentation for both p.o. and i.p. administrations. Furthermore, the data indicate the possible involvement of EC reuptake/transport in pathophysiological processes related to pain and inflammation.

Pirfenidone Induces G1 Arrest in Human Tenon's Fibroblasts In Vitro Involving AKT and MAPK Signaling Pathways

PURPOSE

To investigate the underlying mechanism by which pirfenidone blocks the transition from the G1 to S phase in primary human Tenon's fibroblasts.

METHODS

Primary human Tenon's fibroblasts were characterized by immunocytofluorescence staining with vimentin, fibroblast surface protein, and cytokeratin. After treating Tenon's fibroblasts with pirfenidone under proliferation conditions (10% fetal bovine serum), cell proliferation was measured using a WST-1 assay. Progression through the cell cycle was analyzed by flow cytometry. The expression of CDK2, CDK6, cyclinD1, cyclinD3, and cyclinE and the phosphorylation of AKT, ERK1/2/MAPK, JNK/MAPK, and p38 MAPK were estimated using western blot analysis.

RESULTS

Under proliferative conditions, pirfenidone inhibited Tenon's fibroblasts proliferation and arrested the cell cycle at the G1 phase; decreased the phosphorylation of AKT, GSK3β, ERK1/2/MAPK, and JNK/MAPK; increased the phosphorylation of p38 MAPK; and inhibited CDK2, CDK6, cyclin D1, cyclin D3, and cyclin E in a dose-dependent manner. Inhibitors of AKT (LY294002), ERK1/2 (U0126), and JNK (SP600125) arrested the G1/S transition, similar to the effect of pirfenidone. The p38 inhibitor (SB202190) decreased the G1-blocking effect of pirfenidone. The expression of CDK2, CDK6, cyclin D1, and cyclin D3 were inhibited by LY294002, U0126, and SP600125. SB202190 attenuated the pirfenidone-induced reduction of CDK2, CDK6, cyclin D1, cyclin D3, and cyclin E.

CONCLUSIONS

Pirfenidone inhibited HTFs proliferation and induced G1 arrest by downregulating CDKs and cyclins involving the AKT/GSK3β and MAPK signaling pathways.

Studies on medicinal herbs for cognitive enhancement based on the text mining of Dongeuibogam and preliminary evaluation of its effects

ETHNOPHARMACOLOGICAL RELEVANCE

In literature on Korean medicine, Dongeuibogam (Treasured Mirror of Eastern Medicine), published in 1613, represents the overall results of the traditional medicines of North-East Asia based on prior medicinal literature of this region. We utilized this medicinal literature by text mining to establish a list of candidate herbs for cognitive enhancement in the elderly and then performed an evaluation of their effects.

MATERIALS AND METHODS

Text mining was performed for selection of candidate herbs. Cell viability was determined in HT22 hippocampal cells and immunohistochemistry and behavioral analysis was performed in a kainic acid (KA) mice model in order to observe alterations of hippocampal cells and cognition.

RESULTS

Twenty four herbs for cognitive enhancement in the elderly were selected by text mining of Dongeuibogam. In HT22 cells, pretreatment with 3 candidate herbs resulted in significantly reduced glutamate-induced cell death. Panax ginseng was the most neuroprotective herb against glutamate-induced cell death. In the hippocampus of a KA mice model, pretreatment with 11 candidate herbs resulted in suppression of caspase-3 expression. Treatment with 7 candidate herbs resulted in significantly enhanced expression levels of phosphorylated cAMP response element binding protein. Number of proliferated cells indicated by BrdU labeling was increased by treatment with 10 candidate herbs. Schisandra chinensis was the most effective herb against cell death and proliferation of progenitor cells and Rehmannia glutinosa in neuroprotection in the hippocampus of a KA mice model. In a KA mice model, we confirmed improved spatial and short memory by treatment with the 3 most effective candidate herbs and these recovered functions were involved in a higher number of newly formed neurons from progenitor cells in the hippocampus.

CONCLUSIONS

These established herbs and their combinations identified by text-mining technique and evaluation for effectiveness may have value in further experimental and clinical applications for cognitive enhancement in the elderly.