Antifolate Research Articles

Low serum level and chronic toxicity for methotrexate. Case Report.

Methotrexate (MTX) is a folic acid antagonist used to treat different immunological or proliferative illnesses because of its anti-proliferative and anti-inflammatory effects. MTX Toxicity is considered a severe problem. Although acute toxicity related to high-dose administration (doses ≥500 mg/m2) can be predicted based on the given dose, chronic toxicity still has no specific factors to predict it, so treatment depends on the history and symptoms of toxicity. MTX was initially used for oncology indications with high cyclic doses, then expanded to non-oncology indications with different low doses and frequencies. This significant change in doses resulted in dosing errors that contributed to MTX toxicity reports. Measures to prevent the toxicity of MTX should be implemented. A 66-year-old female patient ingested 10 mg of MTX daily for one month instead of the once-toxicity symptoms. The serum level of MTX was requested, and treatment with folinic acid was initiated until the patient improved with the discontinuation of MTX. There is limited literature about the lack the total cumulative dose, duration of intake, or serum level of MTX. All this information was provided in this case report, but drug-drug interactions were not reviewed, although aspirin and pantoprazole were identified as having interactions with methotrexate in this patient. Minimum total cumulative dose identification may help assess the toxicity risk in such patients. Low-dose MTX chronic toxicity still needs further information to guide the patient's risk of toxicity and when to initiate treatment. Safety-practical measures should be implemented to prevent such administration errors.

Considerations in the management of ocular toxoplasmosis in pregnancy: a review of literature.

Ocular toxoplasmosis is the most common cause of infectious posterior uveitis. Available literature is still conflicting regarding the incidence of recurrence during pregnancy as various calculations were employed in the different published studies. Although earlier reports have suggested a difference in presentation and an increase in severity during pregnancy, newer studies appear to show otherwise. Further diagnostic testing, including serologic and intraocular fluid sampling, may be indicated to increase the diagnostic accuracy in this special population of patients. The management of ocular toxoplasmosis during pregnancy is challenging as the foetus is additionally considered in the choice of treatment. Traditionally preferred anti-toxoplasmosis regimens containing antifolate drugs, such as pyrimethamine and trimethoprim-sulfamethoxazole, cannot be used routinely in pregnant patients, especially during the first trimester. This review includes literature on alternative treatments for ocular toxoplasmosis during pregnancy, including spiramycin and intravitreal treatment options.

Effect of vitamin B12 on methotrexate-induced cardiotoxicity in rats.

Methotrexate (MTX) is a drug with anti-inflammatory and immunosuppressive effects and is also a folic acid antagonist. Our aim in this study is to determine the molecular mechanisms of cardiotoxicity caused by MTX, a chemotherapeutic drug, and to evaluate the protective effects of vitamin B12 on this toxicity. A total of 32 rats were used in our study and 4 groups were formed. Control group, Vit B12 group (3 μg/kg B12 for 15 days, IP), MTX group (20 mg/kg MTX single dose on day 8 of the experiment, IP), MTX +Vit B12 group (3 μg/kg, IP ), Vit B12 throughout the 15 days, and a single dose of 20 mg/kg MTX (IP) on day 8 of the experiment. Immunohistochemically, expressions of hypoxia-inducible factor 1α (HIF1-α), vascular endothelial growth factor receptor-2 (VEGFR-2), erythropoietin (EPO), and interleukin-6 (IL-6) were evaluated in the heart tissue. Total catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA) levels were measured in the heart tissue. At the same time, ANP and NT-proBNP levels were measured in the blood serum. In the study, the expression of HIF1-α and VEGFR-2 increased significantly in the MTX group, while IL-6 and EPO significantly decreased. At the same time, CAT and SOD levels were significantly decreased and MDA levels increased significantly in the MTX group. While vitamin B12 significantly corrected all these values, it also greatly reduced the increases in ANP and NT-proBNP levels caused by MTX. It is important to use Vit B12 before and after MTX administration to replace the folate that MTX has reduced.

Disproportionality Analysis of Stomatitis Associated with Anticancer Drugs Using the Japanese Adverse Drug Event Report Database

Introduction: Anticancer drug-induced stomatitis can affect a patient’s quality of life and the continuation of drug treatment. Although there have been reports of the occurrence of stomatitis associated with anticancer agents in clinical trials, few Japanese participants have been enrolled in clinical trials and have not been sufficiently investigated. In addition, there has been little attention on research on anticancer drugs associated with stomatitis by patient stratification with different carcinogenic sites. Therefore, the aim of this study was to determine the disproportionality associated with stomatitis for various types of anticancer drugs in different types of cancer patients using the Japanese Adverse Drug Event Report (JADER) database. Methods: The aim of this study was to identify the disproportionality of stomatitis by analyzing the type of anticancer drug and cancer patients using the Japanese Pharmacovigilance Database. Data obtained from spontaneous reports of adverse events with more than 10 stomatitis outbreaks reported in the JADER database between April 2004 and March 2023 were analyzed. The safety signal for an adverse event was defined as the lower limit of the 95% confidence interval of the reported odds ratio of >1. Results: There were 6,178 reports of drugs associated with stomatitis. Among these, 41 drugs were suggested to be associated with stomatitis, and 41 drugs were detected as signals. These drugs were classified based on their efficacy: antipyrimidines (six drugs), folate metabolism antagonists (three drugs), alkylating agents (four drugs), platinum (three drugs), topoisomerase inhibitors (three drugs), microtubule inhibitors (three drugs), mammalian target of rapamycin (mTOR) inhibitors (two drugs), kinase inhibitors (seven drugs), anti-growth factor antibodies (five drugs) immune checkpoint inhibitors (one drug), and others (four drugs). Conclusion: The drugs that may be associated with stomatitis were cell cycle-dependent drugs, epidermal growth factor receptor-tyrosine kinase inhibitors, and mTOR inhibitors. Moreover, this study suggested that anti-growth factor antibodies and immune checkpoint inhibitors may be associated with stomatitis development.

Methotrexate-induced Hyperpigmentation in a Patient with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic progressive systemic and inflammatory disease affecting the lining of the synovial membranes, leading to inflammatory polyarthritis and extraarticular involvement in a symmetrical way. RA is known to be an autoimmune condition, which means that the body’s natural self-defense system gets confused and starts to attack the body’s healthy tissues. Treatment of RA is usually with disease-modifying antirheumatic drugs (DMARDs), but if left untreated, the risk of morbidity, mortality rate, and socioeconomic burdens will increase. Methotrexate (MTX) is one of the folic acid antagonists and one of the conventional synthetic DMARDs. It is the most common drug for the treatment of RA. MTX is a dihydrofolate reductase inhibitor that decreases purine metabolism, which affects cell division. MTX can also cause different types of cutaneous side effects, such as acral erythema, urticaria, ulcerations of the oral mucosa, burning sensation of the skin, multiform erythema, vasculitis, and hyperpigmentation to sun-exposed area. In this case report, we describe a 31-year-old woman who had RA and then developed MTX-induced hyperpigmentation.

Non-surgical management of patients with ectopic pregnancy: A review

An ectopic pregnancy is a medical emergency. Currently, surgery is the main method of therapy, and non-surgical management with methotrexate is considered an acceptable alternative. Methotrexate is a folic acid antagonist and has an inhibitory effect on the proliferation of trophoblast cells. There are various methotrexate regimens; the choice is based on the level of β-subunit of human chorionic gonadotropin, the location of the ectopic pregnancy and the patient's adherence to treatment. Therapy of ectopic tubal pregnancy with methotrexate is an effective and safe alternative to surgical treatment, does not affect the ovarian reserve and preserves the woman's fertility.

Structure-based design, and development of amidinyl, amidoximyl and hydroxamic acid based organic molecules as novel antimalarial drug candidates

Malaria remains a significant global health concern causing numerous fatalities and the emergence of antimalarial drug resistance highlights the urgent need for novel therapeutic options with innovative mechanisms of action and targets. This study aimed to design potential inhibitors of Plasmodium falciparum 6-pyruvoyltetrahydropterin synthase (PfPTPS), synthesize them, and experimentally validate their efficacy as antimalarial agents. A structure-based approach was employed to design a series of novel derivatives, including amidinyl, amidoximyl and hydroxamic acid analogs (1c, 1d, 2b, and 3b), with a focus on their ability to bind to the Zn2+ present in the active site of PfPTPS. The syntheses of these compounds were accomplished through various multi-step synthetic pathways and their structural identities were confirmed using 1H and 13C NMR spectra, mass spectra, and elemental analysis. The compounds were screened for their antiplasmodial activity against the NF54 strain of P. falciparum and in vitro cytotoxicity testing was performed using L-6 cells. The in vivo acute toxicity of the compounds was evaluated in mice. Docking studies of the compounds with the 3D structure of PfPTPS revealed their strong binding affinities, with compound 3b exhibiting notable metal–acceptor interaction with the Zn2+ in the protein binding pocket thereby positioning it as a lead compound for PfPTPS inhibition. The in vitro antiplasmodial studies revealed moderate efficacies against the Pf NF54 strain, particularly compounds 1d and 3b which displayed IC50 < 0.2 μM. No significant cytotoxicity was noted on the L-6 rat cell line. Moreover, in vivo studies suggested that compound 3b exhibited both safety and efficacy in treating rodent malaria. The identified lead compound in this study represents a possible candidate for antimalarial drug development and can be further explored in the search for alternative antifolate drugs to combat the malaria menace.

Folate deficiency reduced aberrant level of DOT1L-mediated histone H3K79 methylation causes disruptive SHH gene expression involved in neural tube defects

BackgroundNeural tube defects (NTDs) are one of the most severe congenital abnormalities characterized by failures of the neural tube to close during early embryogenesis. Maternal folate deficiency could impact the occurrence of NTDs, however, the mechanisms involved in the cause of NTDs are poorly defined.ResultsHere, we report that histone H3 methyltransferase disruptor of telomeric silencing 1-like (DOT1L) expression was significantly downregulated, and low levels of H3K79me2 were found in the corresponding NTDs samples with their maternal serum folate under low levels. Using ChIP-seq assays, we found that a decrease of H3K79me2 downregulates the expression of Shh and Sufu in mouse embryonic stem cells (mESC) under folate deficiency. Interestingly, folate antagonist methotrexate treatment led to attenuation of H3K79me2 due to Dot1l, affecting Shh and Sufu genes regulation. Upon further analysis, we find that the genes Shh and Sufu are both downregulated in the brain tissues of mice and humans with NTDs. There was a positive correlation between the transcription levels of Shh, Sufu and the protein levels of DOT1L by Pearson correlation analysis.ConclusionOur results indicate that abnormal Shh and Sufu genes expression reduced by aberrant Dot1l-mediated H3K79me2 levels could be the cause of NTDs occurrence.

Protective effects of empagliflozin on methotrexate induced hepatotoxicity in rats

Methotrexate (MTX), a folic acid antagonist, is commonly prescribed as a cytotoxic drug to treat several conditions such as leukemia and inflammation-related diseases, including rheumatoid arthritis and psoriasis. However, its use in clinical practice has been limited due to its fatal side effects, especially hepatotoxicity. Empagliflozin is a sodium-glucose cotransporter 2 (SGLT2) inhibitor that has recently been reported to exhibit anti-inflammatory and anti-oxidative properties. This study was aimed to evaluate the effect of Empagliflozin on liver injury induced by MTX in rats. The rats were divided into five groups as control, MTX (20 mg/kg; i.p.), Empagliflozin (30 mg/kg/day; i.p.), MTX and Empagliflozin (10 and 30 mg/kg/day; i.p.). Histopathologic alterations were examined for assessment of the liver injury. Furthermore, the levels of tissue malondialdehyde (MDA) and activity of anti-oxidative enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase, as well as serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were evaluated. Our results revealed that treatment with Empagliflozin significantly improved histopathologic alterations, and elevated levels of AST and ALT induced by MTX administration. Additionally, altered activities of SOD, GPx, and catalase were significantly improved followed by Empagliflozin treatment. However, the higher dose of Empagliflozin was observed to have several benefits compared to the lower dose. Our data suggest that Empagliflozin might possess a protective role against MTX-induced hepatotoxicity by inhibiting oxidative stress in liver tissue.

Pralatrexate injection combined with CHOP for treatment of PTCL: results from the Fol-CHOP dose-finding phase 1 trial

AbstractPralatrexate is a folate antagonist that selectively enters cells expressing reduced folate carrier type 1 and competitively inhibits dihydrofolate reductase, leading to interruption of RNA synthesis, DNA replication, and apoptosis. This phase 1 study was conducted to evaluate the maximum tolerated dose (MTD) of pralatrexate in combination with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) regimen (part 1) and the response and pharmacokinetics of 6 cycles of this combination (CHOP + Folotyn 30 mg/m2 [Fol-CHOP]) in patients with newly diagnosed peripheral T-cell lymphoma (PTCL). In part 1, on days 1 and 8 of each cycle, patients were treated with 10, 15, 20, 25, or 30 mg/m2 of pralatrexate in combination with CHOP, per dose escalation, in 5 sequential cohorts. No patients experienced DLTs in cohorts 1, 2, 3, 4, and 5. The pralatrexate dose of 30 mg/m2 was selected to be combined with CHOP for part 2 and administered to 33 additional patients in the expansion cohort. At the MTD, the Fol-CHOP regimen was generally well tolerated in patients with PTCL, with an overall response rate (ORR) of 83.9% (20 complete response and 6 partial response), as assessed by treating investigators. Thirty-five patients (67.3%) experienced grade 3/4 treatment-emergent adverse events, the most common of which were anemia (21.2%), neutropenia (19.2%), febrile neutropenia (11.5%), fatigue, mucosal inflammation, nausea, and vomiting (7.7% each). In conclusion, Fol-CHOP was found to be a safe and effective treatment for newly diagnosed PTCL and deemed worthy of further investigation. This trial was registered at www.ClinicalTrials.gov as #NCT02594267.

Folate-functionalized CoFe2O4 nanozyme inspired by folate antagonist effect for methotrexate detection with high anti-interference ability and recyclability

Methotrexate (MTX) is a widely used chemotherapeutic drug to treat cancer and autoimmune diseases, which has a narrow therapeutic window and can cause systemic toxicity. The monitoring of MTX is therefore of crucial importance in clinical practice and precision medication. However, current detection techniques suffer from limitations in cost and time effectiveness, making them unsuitable for out-of-lab and point-of-care testing. Inspired by the antimetabolite mechanism of MTX, a signal-on colorimetric sensing platform based on CoFe2O4 nanozyme functionalized with folic acid (FA@CoFe2O4) was elaborately developed to monitor MTX. Due to the ability of the immobilized folate to be reduced by dihydrofolate reductase (DHFR) to tetrahydrofolate, it poses competitive effect on the chromogenic substrate by its strong reducibility when FA@CoFe2O4 exerts its peroxidase-like activity, thereby inhibiting the discoloration of the substrate. Once MTX is introduced, the active sites of DHFR will preferentially bind to it, leading to suppression in the generation of tetrahydrofolate and further restoring the substrate’s color rendering. Based on this principle, the developed sensing strategy exhibited a broad range from 0.1 μM to 40 μM towards MTX detection. In addition, the magnetic property endowed the FA@CoFe2O4 nanozyme excellent recyclability and allowed the MTX detection with high anti-interference ability from other drugs and coexisting antioxidants. The feasibility of the method was validated by monitoring MTX level in human serums. This work paves a new way towards therapeutic drug monitoring that serves personalized administration.

Characteristics of antibiotic resistance of non-typhoidal Salmonella circulating in the Russian Federation in the period from 2019 to 2022

Introduction. Non-typhoidal Salmonella make a significant contribution to the incidence of enteric infections and are characterized by an increasing proportion of strains resistant to antimicrobial agents (AMA), including the first choice antibiotics (cephalosporins III and fluoroquinolones).&#x0D; The purpose of the study is to assess the phenotypic resistance of Salmonella to various classes of AMAs and determine the relationship between the phenotypic resistance, serotype, source of isolation and nature of incidence.&#x0D; Materials and methods. We studied 752 representative strains of Salmonella of 2494 strains isolated from various sources (clinical samples, food products, environment) received from 59 regions of Russia in the period from 2019 to 2022. The phenotypic resistance to 22 antibiotics of 11 CLSI classes of AMAs was assessed by broth microdilution method (minimum inhibitory concentration). The diversity of resistance profiles of Salmonella serotypes was compared using the Shannon index.&#x0D; Results. The dominant position in terms of isolation frequency is occupied by the serotypes Salmonella Enteritidis, S. Infantis, S. Muenchen, S. Typhimurium, S. Bovismorbificans, which accounted for 64.4% of the studied strains. 543 (72.2%) strains showed resistance to at least one of the tested antibiotics; 193 (25.7%) strains were characterized by multidrug resistance phenotype (MDR). Resistance to AMA classes was characterized by the following distribution: quinolones (61.3%), tetracyclines (28.1%), penicillins (19.1%), β-lactam combination agents (18.6%), folate pathway antagonists (16, 5%), phenicols (10.1%), aminoglycosides (5.6%), cephems (4.7%), monobactams (4.4%), lipopeptides (3.9%). No penem-resistant strains have been identified. The features of Salmonella resistance by AMA classes are shown to depend on the sources of isolation, the Salmonella serotype and the nature of the incidence (outbreak and sporadic).&#x0D; Conclusions. Monitoring of phenotypic antibiotic resistance is an important tool for epidemiological surveillance in order to prevent the spread of bacterial resistance to AMAs.

Methotrexate Polyglutamate Concentrations as a Possible Predictive Marker for Effectiveness of Methotrexate Therapy in Patients with Sarcoidosis: A Pilot Study.

Methotrexate (MTX), a folate antagonist, is often used as second-line treatment in patients with sarcoidosis. Effectiveness of MTX has large inter-patient variability and at present therapeutic drug monitoring (TDM) of MTX is not possible. Upon administration, MTX is actively transported into cells and metabolized to its active forms by adding glutamate residues forming MTXPG(n=1-5) resulting in enhanced cellular retention. In this study we address the question whether different MTXPG(n) concentrations in red blood cells (RBC) of patients with sarcoidosis after 3months of MTX therapy correlate with response to treatment. We retrospectively included patients with sarcoidosis that had started on MTX therapy and from whom blood samples and FDG-PET/CT were available 3 and 6-12months after MTX initiation, respectively. FDG-uptake was measured by SUVmax in the heart, lungs and thoracic lymph nodes. Changes in SUVmax was used to determine anti-inflammatory response after 6-12months of MTX therapy. MTXPG(n) concentrations were measured from whole blood RBC using an LC-MS/MS method. Pearson correlation coefficients were calculated to evaluate the relationship betweenchanges in the SUVmax andMTXPG(n) concentrations. We included 42 sarcoidosis patients treated with MTX (15mg/week); 31 with cardiac sarcoidosis and 11 with pulmonary sarcoidosis. In MTXPG3 and MTXPG4 a significant negative relation between the absolute changes in SUVmax and MTXPG(n) was found r = - 0.312 (n = 42, p = 0.047) for MTXPG3 and r = - 0.336 (n = 42, p = 0.031 for MTXPG4). The other MTXPG(n) did not correlate to changes in SUVmax. These results suggest a relation between MTXPG(n) concentrations and the anti-inflammatory effect in patients with sarcoidosis. Further prospective validation is warranted, but if measuring MTXPG concentrations could predict treatment effect of MTX this would be a step in the direction of personalized medicine.

A Comparative Study on Antimicrobial Resistance in Escherichia coli Isolated from Channel Catfish and Related Freshwater Fish Species

Antimicrobial resistance (AMR) trends in 114 generic Escherichia coli isolated from channel catfish and related fish species were investigated in this study. Of these, 45 isolates were from commercial-sized channel catfish harvested from fishponds in Alabama, while 69 isolates were from Siluriformes products, accessed from the U.S. Department of Agriculture Food Safety and Inspection Service’ (FSIS) National Antimicrobial Resistance Monitoring System (NARMS) program. Antibiotic susceptibility testing and whole genome sequencing were performed using the GenomeTrakr protocol. Upon analysis, the fishpond isolates showed resistance to ampicillin (44%), meropenem (7%) and azithromycin (4%). The FSIS NARMS isolates showed resistance to tetracycline (31.9%), chloramphenicol (20.3%), sulfisoxazole (17.4%), ampicillin (5.8%) and trimethoprim-sulfamethoxazole, nalidixic acid, amoxicillin-clavulanic acid, azithromycin and cefoxitin below 5% each. There was no correlation between genotypic and phenotypic resistance in the fishpond isolates, however, there was in NARMS isolates for folate pathway antagonists: Sulfisoxazole vs. sul1 and sul2 (p = 0.0042 and p < 0.0001, respectively) and trimethoprim-sulfamethoxazole vs. dfrA16 and sul1 (p = 0.0290 and p = 0.013, respectively). Furthermore, correlations were found for tetracyclines: Tetracycline vs. tet(A) and tet(B) (p < 0.0001 each), macrolides: Azithromycin vs. mph(E) and msr(E) (p = 0.0145 each), phenicols: Chloramphenicol vs. mdtM (p < 0.0001), quinolones: Nalidixic acid vs. gyrA_S83L=POINT (p = 0.0004), and β-lactams: Ampicillin vs. blaTEM-1 (p < 0.0001). Overall, we recorded differences in antimicrobial susceptibility testing profiles, phenotypic-genotypic concordance, and resistance to critically important antimicrobials, which may be a public health concern.

Pemetrexed ameliorates Con A-induced hepatic injury by restricting M1 macrophage activation

Autoimmune hepatitis (AIH), characterized by immune-driven liver destruction and cytokine production, is a progressive inflammatory liver condition that may progress to hepatic cirrhosis or tumors. However, the underlying mechanism is not well understood, and the treatment options for this disease are limited. Pemetrexed (PEM), a clinically used anti-folate drug for treating various tumors, was found to inhibit the nuclear factor (NF)-κB signaling pathways that exert an important role in the development of AIH. Here, we investigated the impact of PEM on immune-mediated hepatic injuries using a murine model of Concanavalin A (Con A)-induced hepatitis, a well-established model for AIH.Mice received intraperitoneal PEM injections 3 times at 12-hour intervals, and two hours later, they were challenged with Con A. Liver samples and serum were collected after 10 h. The results indicate that PEM significantly improved mouse survival rates and lowered serum transaminase levels. Moreover, PEM effectively alleviated oxidative stress, reduced histopathological liver damage, and mitigated hepatocyte apoptosis. Notably, it reduced the activation of M1-type macrophages in the liver. The expression of proinflammatory cytokines and genes associated with M1 macrophages, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-12, IL-1β, and inducible nitric oxide synthase (iNOS), was also decreased. Finally, the results indicated that PEM regulates M1 macrophage activation by modulating the NF-κB signaling pathways.Overall, these results demonstrate that PEM effectively guards against immune-mediated hepatic injuries induced by Con A by inhibiting M1 macrophage activation through the NF-κB signaling pathways and indicate the potential of PEM as a practical treatment option for AIH in clinical settings.

Alpha-linolenic acid protects against methotrexate-induced nephrotoxicity in mouse kidney cells.

Methotrexate (MTX) is a folic acid antagonist used in chronic inflammatory diseases and various cancer treatments. Although the main mechanism of the toxic effect of MTX is not known, it is stated that it causes oxidative stress and inflammation. Alpha-linolenic acid (ALA) protects against oxidative stress, apoptosis, and inflammation. For this reason, we aimed to find out the useful effect of ALA on MTX-induced nephrotoxicity MATERIALS AND METHODS: The mice were divided into 4 groups randomly. The control group was treated with physiological saline solution; the ALA group was treated with ALA (200 mg/kg) by gavage; MTX-treated group received 20 mg/kg i.p. (intraperitoneal) MTX; and MTX+ALA treated group received 20 mg/kg i.p. MTX and ALA 200 mg/kg by gavage. All of the drugs were performed once a day for 9 days. Alpha-linolenic acid significantly decreased oxidative stress parameters and MTX-induced inflammatory and apoptotic mediators. Furthermore, histopathological examination showed that MTX induced significant edematous damage, and ALA treatment attenuated this damage in renal tissue. Our results revealed that ALA may be helpful against MTX-induced nephrotoxicity in mice via its antioxidant and anti-inflammatory properties.

Dimethyl Fumarate Attenuates Methotrexate Hepatotoxicity in Mice Via the Nrf2/HO-1/Anti-Apoptotic Signaling Pathway

Background: Methotrexate (MTX), a folate antagonist used to treat cancer and inflammatory diseases, is known to generate reactive oxygen species. Objectives: The research investigates the impact of dimethyl fumarate (DMF), a nuclear factor erythroid 2-related factor 2 (Nrf2) activator, on an MTX-induced mouse hepatotoxicity model. Methods: Forty-two mice were divided into 6 groups: Control, MTX, DMF 120, and 3 groups of MTX co-treated with DMF 30, 60, and 120 mg/kg. Dimethyl fumarate was gavaged once daily for 10 days. On the fifth day, the animals received MTX 20 mg/kg intraperitoneally. On the eleventh day, the animals were sacrificed, and serum and liver samples were collected to assess the level of oxidative/anti-oxidative and apoptotic/anti-apoptotic markers. Results: Dimethyl fumarate prevented the increase of liver function enzymes, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) induced by MTX (P &lt; 0.001). It prevented the increase in AST and ALT levels, indicating liver recovery (P &lt; 0.001). Furthermore, DMF restored antioxidant markers superoxide dismutase, catalase, glutathione peroxidase, and total thiol while reducing the level of thiobarbituric acid reactive substances (P &lt; 0.001). Dimethyl fumarate also downregulated hepatic mRNA expression of caspase 3 and upregulated Bcl-2, heme oxygenase 1, and Nrf2 genes in MTX co-treated DMF groups. Conclusions: Dimethyl fumarate alleviates oxidative stress and apoptosis, which may be achieved by the Nrf2/HO-1 pathway. Therefore, DMF may be clinically effective in preventing or treating MTX-induced hepatotoxicity.

Association of health, nutrition, and socioeconomic variables with global antimicrobial resistance: a modelling study

Although antimicrobial use is a key selector for antimicrobial resistance, recent studies have suggested that the ecological context in which antimicrobials are used might provide important factors for the prediction of the emergence and spread of antimicrobial resistance. We used 1547 variables from the World Bank dataset consisting of socioeconomic, developmental, health, and nutritional indicators; data from a global sewage-based study on antimicrobial resistance (abundance of antimicrobial resistance genes [ARGs]); and data on antimicrobial usage computed from the ECDC database and the IQVIA database. We characterised and built models predicting the global resistome at an antimicrobial class level. We used a generalised linear mixed-effects model to estimate the association between antimicrobial usage and ARG abundance in the sewage samples; a multivariate random forest model to build predictive models for each antimicrobial resistance class and to select the most important variables for ARG abundance; logistic regression models to test the association between the predicted country-level antimicrobial resistance abundance and the country-level proportion of clinical resistant bacterial isolates; finite mixture models to investigate geographical heterogeneities in the abundance of ARGs; and multivariate finite mixture models with covariates to investigate the effect of heterogeneity in the association between the most important variables and the observed ARG abundance across the different country subgroups. We compared our predictions with available clinical phenotypic data from the SENTRY Antimicrobial Surveillance Program from eight antimicrobial classes and 12 genera from 56 countries. Using antimicrobial use data from between Jan 1, 2016, and Dec 31, 2019, we found that antimicrobial usage was not significantly associated with the global ARG abundance in sewage (p=0·72; incidence rate ratio 1·02 [95% CI 0·92-1·13]), whereas country-specific World Bank's variables explained a large amount of variation. The importance of the World Bank variables differed between antimicrobial classes and countries. Generally, the estimated global ARG abundance was positively associated with the prevalence of clinical phenotypic resistance, with a strong association for bacterial groups in the human gut. The associations between bacterial groups and ARG abundance were positive and significantly different from zero for the aminoglycosides (three of the four of the taxa tested), β-lactam (all the six microbial groups), fluoroquinolones (seven of nine of the microbial groups), glycopeptide (one microbial group tested), folate pathway antagonists (four of five microbial groups), and tetracycline (two of nine microbial groups). Metagenomic analysis of sewage is a robust approach for the surveillance of antimicrobial resistance in pathogens, especially for bacterial groups associated with the human gut. Additional studies on the associations between important socioeconomic, nutritional, and health factors and antimicrobial resistance should consider the variation in these associations between countries and antimicrobial classes. EU Horizon 2020 and Novo Nordisk Foundation.

Detection and genomic characterization of a multidrug-resistant Salmonella Newport co-harbouring blaCMY-2, qnrB19 and mcr-9 from the diarrheic faeces of a foal

ObjectivesThis study reports the genomic characterization of the multidrug resistant Salmonella Newport strain 195_20 recovered from the diarrheic faeces of a foal in Brazil and co-harbouring the mcr-9, blaCMY-2 and qnrB19 antibiotic resistance genes. MethodsBacterial isolate positive for mobile colistin resistance gene (mcr-9) was submitted to antimicrobial susceptibility testing by disk diffusion and broth microdilution for colistin and polymyxin B. The isolate was submitted to whole genome sequencing by Illumina technology and Nanopore Sequencing. Conjugation assays, plasmid sizes determined by S1-PFGE and plasmid content were investigated by hybrid assembly after MinIon long reads sequencing. ResultsIsolate 195_20 was identified as sequence type ST45, resistant to penicillin and cephalosporins (ampicillin, ceftazidime, ceftriaxone and cefotaxime), aminoglycosides (streptomycin and gentamicin), phenicol (chloramphenicol), quinolones and fluoroquinolones (nalidixic acid, ciprofloxacin, and pefloxacin), folate pathway antagonists (sulfonamides and trimethoprim-sulfamethoxazole), and tetracycline. A transferable IncHI2/IncHI2A plasmid sized ca. 262kb was found to carry the mcr-9 gene in a module consisting of IS903-mcr-9-wbuC-IS26. In addition, an 174kb IncC and a 48kb IncN plasmid were also identified in the 195_20 isolate, carrying blaCMY-2 and qnrB19, respectively. ConclusionsNot surprisingly, isolate 195_20 was susceptible to polymyxins, possibly due to absence of qseBC regulatory operon. Presence of mobile colistin resistance (mcr-9), third-generation cephalosporins (blaCMY-2) and quinolone (qnrB19) resistance determinants in zoonotic pathogens from animals in close contact with humans alerts for the possible route of transmission between these different reservoirs.

The Expression and Activation of the NF-κB Pathway Correlate with Methotrexate Resistance and Cell Proliferation in Acute Lymphoblastic Leukemia.

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Although its prognosis continually improves with time, a significant proportion of patients still relapse from the disease because of the leukemia's resistance to therapy. Methotrexate (MTX), a folic-acid antagonist, is a chemotherapy agent commonly used against ALL and as an immune-system suppressant for rheumatoid arthritis that presents multiple and complex mechanisms of action and resistance. Previous studies have shown that MTX modulates the nuclear factor kappa B (NF-κB) pathway, an important family of transcription factors involved in inflammation, immunity, cell survival, and proliferation which are frequently hyperactivated in ALL. Using a gene set enrichment analysis of publicly available gene expression data from 161 newly diagnosed pediatric ALL patients, we found the Tumor necrosis factor α (TNF-α) signaling pathway via NF-κB to be the most enriched Cancer Hallmark in MTX-poor-responder patients. A transcriptomic analysis using a panel of ALL cell lines (six B-cell precursor acute lymphoblastic leukemia and seven T-cell acute lymphoblastic leukemia) also identified the same pathway as differentially enriched among MTX-resistant cell lines, as well as in slowly dividing cells. To better understand the crosstalk between NF-κB activity and MTX resistance, we genetically modified the cell lines to express luciferase under an NF-κB-binding-site promoter. We observed that the fold change in NF-κB activity triggered by TNF-α (but not MTX) treatment correlated with MTX resistance and proliferation across the lines. At the individual gene level, NFKB1 expression was directly associated with a poorer clinical response to MTX and with both an increased TNF-α-triggered NF-κB activation and MTX resistance in the cell lines. Despite these results, the pharmacological inhibition (using BAY 11-7082 and parthenolide) or stimulation (using exogenous TNF-α supplementation) of the NF-κB pathway did not alter the MTX resistance of the cell lines significantly, evidencing a complex interplay between MTX and NF-κB in ALL.