Pirfenidone activates cannabinoid receptor 2 in a mouse model of bleomycin-induced pulmonary fibrosis

Pirfenidone mitigates demyelination and electrophysiological alterations in multiple sclerosis: Targeting NF-κB, sirt1, and neurotrophic genes

Multiple sclerosis (MS) is a demyelinating disease affecting the central nervous system associated with progressive neurodegeneration. Pirfenidone (Pir) is a well-known antifibrotic agent; however, Pir's function in MS is little explored. We evaluated the neuroprotective effects of Pir in MS and its possible underlying mechanisms. Forty male Swiss mice were divided equally into control, cuprizone (CPZ), Pir, and CPZ + Pir groups. Assessment of motor function was conducted using neurobehavioral tests, EMG, and nerve conduction velocity (NCV). Mice's brains were extracted to measure oxidative stress, neuroinflammatory markers, and the expression of neurotrophic genes. The corpus callosum and the sciatic nerve were subjected to histopathological and immunohistochemical studies. The CPZ group was associated with significant reductions in muscle power, frequency of contraction, sciatic NCV, SOD, IL-10, SIRT1, NGF, and neuregulin-1. Significant increases in MDA, TNF-α, INF-γ, IL-17, TGF-β, and NF-κB were also detected. Multiple areas of partially demyelinated nerve fibers in the corpus callosum, the loss of oligodendrocyte nuclei, and increased microglia and astrocytes were also observed. The sciatic nerve revealed partial demyelination with significantly reduced myelin basic protein (MBP) expression. Pir significantly restored motor function, demyelination, and neurodegenerative changes induced by CPZ. Besides the antifibrotic action of Pir, we concluded that it improves motor function in MS by alleviating the demyelinating process and neurodegeneration. Its potential anti-inflammatory, antioxidant, and antifibrotic properties could be contributing factors. These effects could be mediated by modulating the NF-κB, SIRT1, NGF, and neuregulin-1 pathways. Pir is a promising agent for treating MS.

Pirfenidone regulates seizures through the HMGB1/TLR4 axis to improve cognitive functions and modulate oxidative stress and neurotransmitters in PTZ-induced kindling in mice

Background

Epilepsy is a neurological disorder characterized by recurrent seizures due to abnormal electrical activity in the brain. Pirfenidone, an antifibrotic drug, has shown anti-inflammatory and antioxidant properties in various disease models, including neurological conditions. However, its potential anticonvulsant effects have not been thoroughly explored. This study aims to evaluate the anticonvulsant potential of pirfenidone in a pentylenetetrazol-induced kindling model of epilepsy, focusing on its effect on seizure activity, cognition, antioxidant profiles, inflammatory markers, neurotransmitter balance, liver enzyme levels, and histopathological changes.

Methods

Healthy male Swiss albino mice were subjected to an acute Increasing Current Electroshock test and chronic pentylenetetrazol-kindling model. Pirfenidone was administered at doses of 100, 200, and 300 mg/kg, orally, with sodium valproate as a standard drug. Seizure severity and cognitive function were assessed in the pentylenetetrazol-kindling model, along with biochemical assays that evaluated antioxidant enzymes, inflammatory markers, neurotransmitter levels, and liver enzyme levels. Histopathological changes were also assessed in the hippocampus and cortex of experimental mice.

Results

Pirfenidone at 200 mg/kg and 300 mg/kg significantly increased Seizure Threshold Current in the Increasing Current Electroshock test, indicating a protective effect against seizures. In the pentylenetetrazol-kindling model, pirfenidone delayed seizure onset and reduced severity, with the 300 mg/kg dose showing the strongest impact. Pirfenidone also demonstrated significant improvements in cognitive function, as evidenced by enhanced performance in passive avoidance and elevated plus maze tests. Antioxidant profiles showed increased levels of superoxide dismutase, catalase, and reduced glutathione, with a corresponding reduction in malondialdehyde and acetylcholinesterase levels. Pirfenidone significantly reduced pro-inflammatory cytokines including interleukin-6, interleukin-1β, transforming growth factor-β, tumor necrosis factor- α, high-mobility group box-1, and toll-like receptor-4, elevated gamma-aminobutyric acid, decreased glutamate levels, modulated aspartate aminotransferase and alanine aminotransferase levels. Histopathological analysis revealed that pirfenidone ameliorated cellular disintegration and neuronal damage in the hippocampus and cortex.

Conclusion

Pirfenidone shows potential as an anticonvulsant, anti-inflammatory, hepatoprotective, and neuroprotective agent, with additional benefits in improving cognition and oxidative stress profiles in epilepsy treatment. Further studies are required to explore its long-term safety and efficacy.

Therapeutic potential of agents targeting cannabinoid type 2 receptors in organ fibrosis

The endocannabinoid system has garnered attention as a potential therapeutic target in a range of pathological disorders. Cannabinoid receptors type 2 (CB2) are a class of G protein-coupled receptors responsible for transmitting intracellular signals triggered by both endogenous and exogenous cannabinoids, including those derived from plants (phytocannabinoids) or manufactured synthetically (synthetic cannabinoids). Recent recognition of the role of CB2 receptors in fibrosis has fueled interest in therapeutic targeting of CB2 receptors in fibrosis. Fibrosis is characterized by the alteration of the typical cellular composition within the tissue parenchyma, resulting from exposure to diverse etiological factors. The pivotal function of CB2 agonists has been widely recognized in the regulation of inflammation, fibrogenesis, and various other biological pathologies. The modulation of CB2 receptors, whether by enhancing their expression or activating their function, has the potential to provide benefits in numerous conditions, particularly by avoiding any associated adverse effects on the central nervous system. The sufficient activation of CB2 receptors resulted in the complete suppression of gene expression related to transforming growth factor β1 and its subsequent fibrogenic response. Multiple reports have also indicated the diverse functions that CB2 agonists possess in mitigating chronic inflammation and subsequent fibrosis development in various types of tissues. While currently in the preclinical stage, the advancement of CB2 compounds has garnered significant attention within the realm of drug discovery. This review presents a comprehensive synthesis of various independent experimental studies elucidating the pivotal role of identified natural and synthetic CB2 agonists in the pathophysiology of organ fibrosis, specifically in the cardiac, hepatic, and renal systems.

Pirfenidone and nintedanib attenuate pulmonary fibrosis in mice by inhibiting the expression of JAK2

Background

Pirfenidone and nintedanib were approved by the Food and Drug Administration (FDA) for the treatment of idiopathic pulmonary fibrosis (IPF). These two drugs can slow the progression of the disease, but the specific mechanisms are not fully understood. In the current study, bleomycin (BLM) induced pulmonary fibrosis in mice was accompanied by high p-JAK2 expression in lung tissue, mainly in the nucleus. The expression of p-JAK2 significantly decreased after intragastric administration of pirfenidone and nintedanib. p-JAK2 is reportedly expressed mainly in the cytoplasm and exerts its effect by activating downstream p-STAT3 in the nucleus.

Methods

In vivo experiments, pulmonary fibrosis was induced in mice with BLM and then treated with pirfenidone and nintedanib. The levels of transforming growth factor-β (TGF-β1), SP-A, SP-D and KL-6 in serum were measured by enzyme-linked immunosorbent assay (ELISA). Pathological staining was performed to assess lung fibrosis in mice, Western blot was performed to detect the expression levels of relevant proteins, and immunofluorescence was performed to observe the fluorescence expression of p-JAK2. In cellular experiments, MLE12 was stimulated with TGF-β1 and intervened with TGF-β1 receptor inhibitor and si-JAK2, pirfenidone and nintedanib, respectively, and the related protein expression levels were detected by Western blot.

Results

In both in vivo and in vitro experiments, pirfenidone and nintedanib were found to attenuate the expression of lung fibrosis markers by inhibiting the expression of JAK2, which may reduce the entry of p-JAK2 into the nucleus by downregulating JAK2 phosphorylation through inhibition of the TGF-β receptor. In contrast, inhibition of JAK2 expression greatly reduced the expression of TGF-β receptor and α-smooth muscles actin (a myofibroblast activation marker).

Conclusions

In both in vivo and in vitro experiments, the present study demonstrated that TGF-β1 promotes JAK2 phosphorylation through a non-classical pathway, and conversely, inhibition of JAK2 expression affects the TGF-β1 signalling pathway. Therefore, we speculate that TGF-β1 and JAK2 signaling pathways interact with each other and participate in fibrosis.

Pirfenidone ameliorates silica-induced lung inflammation and fibrosis in mice by inhibiting the secretion of interleukin-17A

Silicosis is a global occupational disease characterized by lung dysfunction, pulmonary inflammation, and fibrosis, for which there is a lack of effective drugs. Pirfenidone has been shown to exert anti-inflammatory and anti-fibrotic properties in the lung. However, whether and how pirfenidone is effective against silicosis remains unknown. Here, we evaluated the efficacy of pirfenidone in the treatment of early and advanced silicosis in an experimental mouse model and explored its potential pharmacological mechanisms. We found that pirfenidone alleviated silica-induced lung dysfunction, secretion of inflammatory cytokines (TNF-α, IL-1β, IL-6) and deposition of fibrotic proteins (collagen I and fibronectin) in both early and advanced silicosis models. Moreover, we observed that both 100 and 200 mg/kg pirfenidone can effectively treat early-stage silicosis, while 400 mg/kg was recommended for advanced silicosis. Mechanistically, antibody array and bioinformatic analysis showed that the pathways related to IL-17 secretion, including JAK-STAT pathway, Th17 differentiation, and IL-17 pathway, might be involved in the treatment of silicosis by pirfenidone. Further in vivo experiments confirmed that pirfenidone reduced the production of IL-17A induced by silica exposure via inhibiting STAT3 phosphorylation. Neutralizing IL-17A by anti-IL-17A antibody improved lung function and reduced pulmonary inflammation and fibrosis in silicosis animals. Collectively, our study has demonstrated that pirfenidone effectively ameliorated silica-induced lung dysfunction, pulmonary inflammation and fibrosis in mouse models by inhibiting the secretion of IL-17A.

CB2-mediated attenuation of nucleus pulposus degeneration via the amelioration of inflammation and oxidative stress in vivo and in vitro

Background

Nucleus pulposus cell (NPC) degeneration is widely accepted as one of the major causes of intervertebral disc (IVD) degeneration (IVDD). The pathogenesis of IVDD is complex and consists of inflammation, oxidative stress, and the loss of extracellular matrix (ECM). Cannabinoid type 2 receptor (CB2) has been shown to be involved in the pathological mechanism of a variety of diseases due to its anti-inflammatory effects and antioxidative stress capacity.

Method

In Vitro, H₂O₂ was used to induce degeneration of nucleus pulposus cells, mRNA and protein expression level was determined by RT-PCR and Western Blot, and Immunocytochemical staining were used to detect expression of collagen II, aggrecan, MMP3/13, superoxide dismutase 2 (SOD2) and inducible nitric oxide synthase (iNOS). In vivo, the potential therapeutic effect of CB2 was detected in the rat acupuncture model.

Result

In vitro, we found that the CB2 agonist (JWH133) treatment reduced the oxidative stress level in NPCs induced by hydrogen peroxide (H₂O₂) treatment. Furthermore, the expression of inflammatory cytokines was also decreased by JWH133 treatment. We found that collagen II and aggrecan expression was preserved, whereas matrix metalloproteinase levels were reduced. In vivo, we established a rat model by needle puncture. Imaging assessment revealed that the disc height index (DHI) and morphology of IVD were significantly improved, and the disc degeneration process was delayed by treatment of JWH133. Furthermore, immunohistochemical (IHC) staining revealed that JWH133 could inhibit the degradation of collagen II and decrease the expression of MMP3.

Conclusions

The experiment indicates the oxidative stress and inflammatory response of rat NPCs induced by H₂O₂ could be inhibited by activating CB2. This study reveals that CB2 activation can effectively delay the development of IVDD, providing an effective therapeutic target for IVDD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00351-x.