Effect of leflunomide on immunological liver injury in mice

Chitosan coated clove oil-based nanoemulsion: An attractive option for oral delivery of leflunomide in rheumatoid arthritis

Rheumatoid arthritis (RA), a distressing inflammatory autoimmune disease, is managed mainly by Disease-modifying antirheumatic drugs (DMARDs), e.g. leflunomide (LEF). LEF (BCS class II) has limited solubility and adverse effects following its systemic exposure. The appealing antirheumatic properties of both clove oil and chitosan (CS) were exploited to design oral leflunomide (LEF)-loaded nanoemulsion (NE) system to augment the therapeutic action of LEF and decrease its systemic side effects as well. Different LEF-NEs were prepared using clove oil, Tween® 20 (surfactant), and PEG 400(co-surfactant) and characterized by thermodynamic stability, percentage transmittance, cloud point, size analysis, and drug content. Optimized LEF-NE was subjected to CS coating forming LEF-CS-NE that exhibited nanometric size range, prolonged drug release, and good physical stability. In vivo anti-rheumatic activity of pure LEF, market LEF, and LEF-CS-NE was assessed utilizing a complete Freund's adjuvant (CFA) rat model. Treatment with LEF-CS-NE reduced edema rate (48.68% inhibition) and caused a marked reduction in interleukin-6 (IL-6) (510.9 ± 2.48 pg/ml), tumor necrosis factor- α (TNF-α) (397.3 ± 2.53 pg/ml), and rheumatoid factor (RF) (42.58 ± 0.49 U/ml). Furthermore, LEF-CS-NE reduced serum levels of glutamic pyruvic transaminase (GPT) to (83.19%) and glutamic oxaloacetic transaminase (GOT) to (40.68%) compared to the control + ve group. The effects of LEF-CS-NE were also superior to both pure and market LEF and showed better results in histopathological studies of paws, liver, kidney, lung, and heart. The remarkable therapeutic and safety profile of LEF-CS-NE makes it a potential oral system for the management of RA.

Leflunomide abrogates neuroinflammatory changes in a rat model of Alzheimer's disease: the role of TNF-α/NF-κB/IL-1β axis inhibition

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases and is associated with disrupted cognition and behavior. Neuroinflammatory pathogenesis is the main component that contributes to AD initiation and progression through microglial activation and neuronal damage. Thus, targeting inflammatory pathways may help manage AD. In this study, for the first time, the potential prophylactic and therapeutic effects of leflunomide were investigated either alone or in combination with rivastigmine in aluminum chloride (AlCl₃)-induced AD-like rats using behavioral, biochemical, and histological approaches. Thirty-six adult male albino rats were divided into two protocols: the treatment protocol, subdivided into five groups (n = 6)-(1) control group, (2) AlCl₃ (50, 70, 100 mg/kg/I.P) group, (3) reference group (rivastigmine 2 mg/kg/P.O.), (4) experimental group (leflunomide 10 mg/kg/P.O.), and (5) combination group (rivastigmine + leflunomide); and the prophylactic protocol (leflunomide 10 mg/kg/P.O.), which started 2 weeks before AlCl₃ induction. The results showed that AlCl₃ disrupted learning and memory parameters in rats and increased amyloid-β plaque deposition and neurofibrillary tangle aggregation. Moreover, AlCl₃ administration markedly elevated acetylcholinesterase activity, nuclear factor-kappa β, tumor necrosis factor-α, and interleukin-1 beta, and marked degenerative changes in the pyramidal neurons. However, administration of leflunomide alone or with rivastigmine in AlCl₃-induced AD rats restored most of the behavioral, biochemical, and histological parameters triggered by AlCl₃ in rats. Our findings suggest that leflunomide can potentially restore most of the neuronal damage in the hippocampal tissues of AlCl₃-induced AD rats. However, these preclinical findings still need to be confirmed in clinical trials.

Leflunomide an immunomodulator with antineoplastic and antiviral potentials but drug-induced liver injury: A comprehensive review

Leflunomide (LF) represents the prototype member of dihydroorotate dehydrogenase (DHODH) enzyme inhibitors. DHODH is a mitochondrial inner membrane enzyme responsible for catalytic conversion of dihydroorotate into orotate, a rate-limiting step in the de novo synthesis of the pyrimidine nucleotides. LF produces cellular depletion of pyrimidine nucleotides required for cell growth and proliferation. Based on the affected cells the outcome can be attainable as immunosuppression, antiproliferative, and/or the recently gained attention of the antiviral potentials of LF and its new congeners. Also, protein tyrosine kinase inhibition is an additional mechanistic benefit of LF, which inhibits immunological events such as cellular expansion and immunoglobulin production with an enhanced release of immunosuppressant cytokines. LF is approved for the treatment of autoimmune arthritis of rheumatoid and psoriatic pathogenesis. Also, LF has been used off-label for the treatment of relapsing-remitting multiple sclerosis. However, LF antiviral activity is repurposed and under investigation with related compounds under a phase-I trial as a SARS CoV-2 antiviral in cases with COVID-19. Despite success in improving patients' mobility and reducing joint destruction, reported events of LF-induced liver injury necessitated regulatory precautions. LF should not be used in patients with hepatic impairment or in combination with drugs elaborating a burden on the liver without regular monitoring of liver enzymes and serum bilirubin as safety biomarkers. This study aims to review the pharmacological and safety profile of LF with a focus on the LF-induced hepatic injury from the perspective of pathophysiology and possible protective agents.

Protective effect of leflunomide against oxidative intestinal injury in a rodent model of sepsis

BACKGROUND

Sepsis is defined as an uncontrolled inflammatory response in a host. The process may lead to severe sepsis, multisystem organ failure and even death. Leflunomide has important immunomodulatory and anti-inflammatory effects, which may mitigate host response to bacterial translocation. The goal of our study was to measure the effects leflunomide administration had on a variety of biochemical markers upregulated in systemic inflammatory response syndrome, sepsis, and multiple organ failure syndrome.

MATERIALS AND METHODS

Wistar albino type rats were randomly divided into five groups: control, sham, leflunomide, sepsis, and sepsis + leflunomide. Sepsis was achieved by means of the cecal ligation and puncture method. Leflunomide 2 × 10 mg/kg/d was administered before the experiment. At the end of 24 h, the tissue levels of superoxide dismutase, catalase activity, malondialdehyde, nitric oxide, and protein carbonyl were measured.

RESULTS

The level of the bowel superoxide dismutase and catalase levels of the sepsis group is significantly lower than those of the control, sham, and leflunomide groups (P < 0.05). Malondialdehyde, nitric oxide, and protein carbonyl levels are significantly higher in sepsis compared with other groups (P < 0.05).

CONCLUSIONS

Leflunomide's prevention of protein and lipid peroxidation was observed in septic bowel tissue. Use of leflunomide could have protective effects against both the onset and the progressive stages of sepsis.

Anti-inflammatory and Anti-arthritic Effects of a Novel Leflunomide Analogue, UTL-5b (GBL-5b)

Rheumatoid arthritis (RA) is a common disease characterized by chronic inflammation and irreversible destruction of articular cartilage and bone. In this report, we examined the anti-inflammatory and anti-arthritic effects of a novel leflunomide analogue, UTL-5b (also known as GBL-5b), for potential RA treatment. Using a carrageenan-induced edema study in rats, UTL-5b exhibited a better anti-inflammatory effect as compared with leflunomide and its metabolite. The chronic efficacy of UTL-5b was examined using type II collagen-induced arthritis (CIA) mouse model. UTL-5b exerted an anti-arthritic effect in a dose-dependant manner with mice given 30 mg/kg exhibiting amelioration of disease early in the trial, but losing statistical significance over time. In contrast, mice treated with 60 mg/kg showed reduced clinical disease parameters early in the trial and these effects were sustained over the ten week trial period. Mechanistic studies indicate that UTL-5b is an inhibitor of TNF-α production in vivo. Oral administration of UTL-5b prior to i.p. injection with lethal dose of lipopolysaccharide (LPS)/D-galactosamine markedly reduced the levels of serum TNF-α and increased survival rates of animals from septic shock-induced death. Acute toxicity study using mice receiving increasing doses of UTL-5b showed that no animals were killed by UTL-5b at 2,000 mg/kg (LD(50) >2,000 mg/kg). Our studies show that UTL-5b represents a novel anti-inflammatory and anti-arthritic agent with potential therapeutic application for RA treatment.

Effect of leflunomide on liver regeneration after partial hepatectomy in rats

PURPOSE

Partial hepatectomy (PH) can be an inevitable surgical therapy in some conditions, such as hepatic malignancies, trauma or partial liver transplantation. Its capacity for regeneration distinguishes the liver from other essential organs. Regeneration is a complex process involving growth factors, cytokines, transcription factors, hormones, and oxidative stress products. In the event of ineffective or total absent liver regeneration, the life threatening picture of acute liver failure may supervene. In the present research, we studied the effect of leflunomide, a novel immunosuppressive and antiinflammatory agent against autoimmune disease, on hepatic regeneration after PH in Wistar Albino rats.

METHODS

Thirty-five Wistar albino rats were divided into five groups: group 1, control; group 2, sham; group 3, drug control (was treated with leflunomide 10 mg/kg/d/i.g.); group 4, PH; group 5, PH + leflunomide. As for PH, approximately 70% of the rat liver was surgically removed under general anesthesia. On postoperative day 3, all rats were humanely killed. Catalase (CAT), superooxide dismutase (SOD) and myeloperoxidase (MPO) activities with malondialdehyde (MDA), nitric oxide and protein carbonyl (PC) levels were determined in remnant liver tissue. Inflammatory process and liver regeneration were evaluated with H&E and KI67, respectively.

RESULTS

The tissue levels of MDA, PC and MPO were lower in group 5 than levels in group 1. PH significantly decreased the enzymatic activity of CAT (p < 0.05) and SOD. This reduction was significantly improved by the treatment with leflunomide. Histopathologically the enhancement of the liver parenchymal regeneration in the group 5 was significantly greater than the group 4.

CONCLUSION

The findings imply that oxidative stress products play a preventive role in liver regeneration after PH and leflunomide ameliorates the regeneration probably by the radical scavenging and antioxidant activities.

Protective effects of leflunomide on intestinal ischemia-reperfusion injury: leflunomide against intestinal ischemia-reperfusion

AIM

The aim of this study was to investigate the possible protective effects of leflunomide, which has antioxidant and anti-inflammatory properties, against intestinal IR injury in rats.

MATERIALS AND METHODS

Forty female Wistar albino rats were divided into six groups: control (n = 5), drug control (n = 7), sham operated (n = 7), IR alone (n = 7), IR plus vehicle (IR + vehicle, n = 7) and IR plus 20 mg/kg leflunomide (IR + Leflunomide, n = 7). While rats were pretreated intragastrically with leflunomide (20 mg/kg) and vehicle in three doses prior to the experiment, respectively, in the IR + Leflunomide and IR + vehicle groups, no additional application was done in the IR alone group. Intestines were exteriorized, and the superior mesenteric artery was occluded for 45 min ischemia, and then the clamp was removed for 120 min reperfusion. After the experiment, the intestines were removed for biochemical and histological examinations. Additionally, blood samples were taken for measurements of antioxidant parameters.

RESULTS

The intestinal IR significantly increased the MDA level and MPO activity; however, treatment with leflunomide reversed those findings (P < 0.05). The CAT activity of the IR + Leflunomide group was significantly higher than in the IR groups (P < 0.05). The SOD activity was increased in the intestinal IR group, and leflunomide treatment reversed that, too (P <0.05). The light microscopic findings showed that IR caused mucosal necrosis and leflunomide treatment reduced the morphological alterations associated with IR (P < 0.05).

CONCLUSION

Intestinal IR injury may be reversed by the anti-inflammatory and antioxidant actions of leflunomide.

Suppressive effect of leflunomide on rat hepatic stellate cell proliferation involves on PDGF-BB-elicited activation of three mitogen-activated protein kinases

In this manuscript, we demonstrated that following stimulus by Kupffer cell-conditioned medium (KCM) and PDGF-BB, hepatic stellate cells (HSCs) showed significant increases in DNA synthesis and PDGFR-beta expression. Furthermore, phosphorylation of PDGFR-beta and three major members of the mitogen-activated protein kinase (MAPK) family were also significantly increased. Studies with respective neutralizing antibodies against released cytokines in conditioned medium demonstrated that PDGF-BB played an essential role in this complex activation process. Administration of A771726, leflunomide's metabolite, markedly blunted these effects. However, the combination of A771726 with any of the three MAPK inhibitors potentiated this inhibitory effect and showed completely blockage on PDGFR-beta expression and phosphorylation. Collectively, these data demonstrate that leflunomide inhibits KCM-mediated HSC proliferation via PDGFR-beta phosphorylation and the subsequent activation of the MAPK pathway. Accordingly, targeted intervention against the PDGF-BB isoform may also offer a promising therapeutic approach to liver fibrosis.

Role of alpha-actin in muscle damage of injured athletes in comparison with traditional markers

OBJECTIVE

In order to identify a reliable marker for the early detection of muscle injuries in sports, alpha-actin protein and other markers of muscle damage were studied in sera of uninjured sportspeople and those with skeletal muscle injury.

METHODS

Blood samples were obtained from 20 sportspeople with skeletal muscle injury and 48 uninjured sportspeople. Immunoassays were performed to determine cardiac troponin I (TnI), troponin T, lactate dehydrogenase and myoglobin concentrations. Western blot and densitometry were used to measure alpha-actin concentrations. Skeletal muscle damage was diagnosed according to physical examination, MRI findings and the biochemical criterion of a creatine kinase value >500 IU/l (Rosalki method, Beckman Instruments SL, Fullerton, California, USA). Results were also compared with previously obtained data on injured and uninjured non-sportspeople.

RESULTS

The mean serum concentration of alpha-actin was significantly higher in sportspeople with muscle damage (10.49 microg/ml) than in uninjured sportspeople (3.99 mcirog/ml). Sera from injured sportspeople showed higher levels of alpha-actin than of troponin or myoglobin. No significant difference in TnI levels was observed between the groups.

CONCLUSIONS

According to these results, alpha-actin is a new and reliable marker of skeletal muscle damage in sportspeople which can be used for the detection of muscle injury. Possible cross interference between skeletal and cardiac muscle damage can be discriminated by the combined use of alpha-actin and TnI. These data suggest that early measurement of alpha-actin in sportspeople with suspected muscle damage will allow them to receive earlier and more effective treatment and to return sooner to the practice of their sport.

Mitochondrial protection by the JNK inhibitor leflunomide rescues mice from acetaminophen-induced liver injury

Acetaminophen (APAP) is a widely used analgesic and antipyretic drug that is safe at therapeutic doses but which can precipitate liver injury at high doses. We have previously found that the antirheumatic drug leflunomide is a potent inhibitor of APAP toxicity in cultured human hepatocytes, protecting them from mitochondria-mediated cell death by inhibiting the mitochondrial permeability transition. The purpose of this study was to explore whether leflunomide protects against APAP hepatotoxicity in vivo and to define the molecular pathways of cytoprotection. Male C57BL/6 mice were treated with a hepatotoxic dose of APAP (750 mg/kg, ip) followed by a single injection of leflunomide (30 mg/kg, ip). Leflunomide (4 hours after APAP dose) afforded significant protection from liver necrosis as assessed by serum ALT activity and histopathology after 8 and 24 hours. The mechanism of protection by leflunomide was not through inhibition of cytochrome P450 (CYP)-catalyzed APAP bioactivation or an apparent suppression of the innate immune system. Instead, leflunomide inhibited APAP-induced activation (phosphorylation) of c-jun NH2-terminal protein kinase (JNK), thus preventing downstream Bcl-2 and Bcl-XL inactivation and protecting from mitochondrial permeabilization and cytochrome c release. Furthermore, leflunomide inhibited the APAP-mediated increased expression of inducible nitric oxide synthase and prevented the formation of peroxynitrite, as judged from the absence of hepatic nitrotyrosine adducts. Even when given 8 hours after APAP dose, leflunomide still protected from massive liver necrosis.

CONCLUSION

Leflunomide afforded protection against APAP-induced hepatotoxicity in mice through inhibition of JNK-mediated activation of mitochondrial permeabilization.

Prevention of renal ischemia/reperfusion-induced injury in rats by leflunomide

OBJECTIVE

There is increasing evidence to suggest that toxic oxygen radicals play an essential role in the pathogenesis of ischemia/reperfusion (I/R) injury in the kidney. This study was designed to investigate the effects of leflunomide, an isoxazole derivative and a unique immunomodulatory agent, in I/R-induced renal injury in rats.

METHODS

Forty female Sprague-Dawley rats were divided equally into four groups: (I) control (only leflunomide 10 mg/kg, intragastrically treated); (II) sham operated (only unilateral nephrectomy); (III) I/R; and (IV) leflunomide (10 mg/kg for two doses prior to experiment) plus I/R groups. In groups III and IV, after unilateral nephrectomy, the rats were subjected to 60 min of left renal pedicle occlusion, followed by 6 h of reperfusion. At the end of the reperfusion period, rats were killed and kidneys and blood were removed. Catalase, myeloperoxidase and xanthine oxidase activities, and malondialdehyde, nitric oxide and protein carbonyl levels were determined in renal tissue. Serum creatinine, blood urea nitrogen and aspartate aminotransferase were measured for the evaluation of renal function. In histopathological examination, renal damage was scored 0-3.

RESULTS

Group III animals demonstrated severe deterioration of renal function, renal morphology and a significant renal oxidative stress. Pretreatment of animals with leflunomide markedly attenuated renal dysfunction, morphological alterations, reduced elevated oxidative stress products levels and restored the depleted renal antioxidant enzyme.

CONCLUSION

The findings imply that oxygen radicals play a causal role in I/R-induced renal injury, and leflunomide exerts renoprotective effects probably by the radical scavenging and antioxidant activities with immunomodulatory effect.

Hepatic damage in biliary-obstructed rats is ameliorated by leflunomide treatment

Cholestasis, or impaired bile flow, occurs in a wide variety of liver diseases and causes hepatic damage by retention and accumulation of toxic hydrophobic bile salts inducing persistent inflammation and oxidative stress. In the present research, we studied the effect of leflunomide, a novel immunosuppressive and anti-inflammatory agent against autoimmune disease, on hepatic damage produced by double ligature of the extrahepatic biliary duct in Wistar Albino rats. Cholestasis was done by double ligature and section of the extrahepatic biliary duct (BDL). Leflunomide was given i.g. 10 mg/kg/day. The severity of cholestasis and hepatic injury was determined by changes in the plasma enzyme activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and levels of direct bilirubin. Malondialdehyde (MDA), protein carbonyl (PC), nitric oxide (NO), catalase (CAT) and superoxide dismutase (SOD) were determined to the oxidative status in the liver tissue. Myeloperoxidase (MPO) activity and levels of tissue hydroxyproline (HPR) were determined to neutrophil activation and collagen accumulation, respectively. Further, histological changes were studied. Treatment with leflunomide markedly reduced serum transaminase activities as compared to BDL rats. At the same time leflunomide significantly inhibited increases in liver MDA, PC and NO levels and also attenuated the depletion of CAT and SOD in the liver after bile duct ligation. Similarly, increase in tissue MPO activity and HPR due to BDL was also attenuated by leflunomide treatment. These findings were supported by histopathological findings. These findings suggested that leflunomide can attenuate hepatic damage in extrahepatic cholestasis by prevention of oxidative stress and inflammatory process.

Protective effects of leflunomide against ischemia-reperfusion injury of the rat liver

Hepatic ischemia-reperfusion (I/R) injury may be developed in some conditions, such as trauma, major hepatic resection, hemorrhagic shock or liver transplantation. I/R injury of the liver causes hepatocellular damage that may lead to hepatic failure. A considerable body of evidence indicates that reactive oxygen species (ROS) and inflammation may contribute to hepatocellular injury in liver I/R. Leflunomide is an isoxazole derivative, and a unique immunomodulatory agent. In the present study, we examined the effects of leflunomide on the neutrophil activation with oxidative stress and some antioxidant enzymes in the reperfusion following I/R in the rat liver. Thirty-two rats divided into four groups: group 1 (control); was given leflunomide 10 mg/kg, i.g.; group 2 (SHAM), animals were only laparotomized; group 3 (liver I/R), and group 4 (liver I/R + Leflunomide). In group 4, rats were pretreated with leflunomide (10 mg/kg, i.g.) two doses prior to experiment. In groups 3 and 4, occluding the hepatic pedicel for 60 min induced ischemia and reperfusion was allowed thereafter for 60 min. At the end of the reperfusion period, rats were sacrificed. superoxide dismutase, catalase, nitric oxide, xanthine oxidase, malondialdehyde, protein carbonyl and myeloperoxidase levels were determined in hepatic tissue as well as histological examination with H and E staining. Group 3 animals demonstrated severe deterioration of liver morphology and a significant liver oxidative stress. Pretreatment of animals with leflunomide markedly attenuated morphological alterations and neutrophil activation, reduced elevated oxidative stress products levels and restored the depleted hepatic antioxidant enzyme. The findings imply that ROS play a causal role in I/R-induced hepatic injury, and leflunomide exerts hepatoprotective effects probably by the anti-inflammatory effect with radical scavenging and antioxidant activities.

The broadening use of leflunomide in clinical practice

Autoimmune diseases make up a large proportion of chronic disease care. Inducing remission by immunosuppression remains the cornerstone of long-term management. This article reviews the place of leflunomide in clinical practice and outlines its potential applications beyond its licenced indication, rheumatoid arthritis.

Antioxidative effects related to the potential anti-aging properties of the Chinese prescription Kangen-karyu and Carthami Flos in senescence-accelerated mice

The popular oxidative stress theory predicts that enhancement of the antioxidative defense system to attenuate free radical-induced damage counteracts the aging process. We used senescence-accelerated mice (SAM) because SAM has been shown to suppress the antioxidative defense system and mitochondrial dysfunction induced by oxidative stress. We investigated the antioxidative effects of the Chinese prescription Kangen-karyu and its crude drug component Carthami Flos. The administration of Kangen-karyu extract at 100 mg/kg body weight per day for 10 weeks inhibited generation of nitric oxide, superoxide and the hydroxyl radical (*OH), while Carthami Flos extract showed only *OH-scavenging activity. Diet supplemented with Kangen-karyu and Carthami Flos extracts enhanced the activities of the antioxidative enzymes superoxide dismutase in hepatic tissue and glutathione peroxidase in renal tissue, and reduced the hepatic lipid peroxidation level which increased with aging, indicating the protective action against oxidative stress by enhancing the antioxidative status. Hepatic and renal dysfunction with aging was also ameliorated by the administration of Kangen-karyu and Carthami Flos supplements. Furthermore, the observed antioxidative properties of the Chinese prescription Kangen-karyu were more evident than those of Carthami Flos. These findings suggest that the protective activity of Kangen-karyu against the oxidative tissue damages during aging may be due partly to synergistic and/or additive effects of its crude preparation. The present study strongly indicates that Kangen-karyu counteract the oxidative stress and ameliorating tissue damage possibly associated with aging in SAM.