Search Results (355)

Epidermolysis Bullosa (EB) comprises a group of inherited blistering disorders caused by pathogenic variants in genes essential for skin and mucosal integrity. Nonsense mutations, which generate premature termination codons (PTCs), result in reduced or absent protein expression and contribute to severe disease phenotypes in EB. Readthrough therapies, which may continue translation past PTCs to restore full-length functional proteins, have emerged as promising approaches. This review summarizes findings from preclinical studies investigating readthrough therapies in EB models, clinical studies demonstrating efficacy in EB patients, and emerging readthrough agents with potential application to EB. Preclinical and clinical studies with gentamicin have demonstrated restored type VII collagen and laminin-332 expression, leading to measurable clinical improvements. Parallel development of novel compounds—including aminoglycoside analogs (e.g., ELX-02), translation termination factor degraders (e.g., CC-90009, SRI-41315, SJ6986), tRNA post-transcriptional inhibitors (e.g., 2,6-diaminopurine, NV848), and nucleoside analogs (e.g., clitocine)—has expanded the therapeutic pipeline. Although challenges remain regarding toxicity, codon specificity, and variable protein restoration thresholds, continued advances in molecular targeting and combination therapies offer the potential to establish readthrough therapies as localized or systemic treatments addressing both cutaneous and extracutaneous disease manifestations in EB. Full article

The incorporation of nucleoside analogs into DNA by polymerases, followed by their removal through base excision repair (BER), represents a promising strategy for cancer chemotherapy. In this study, we investigated the incorporation and cytotoxic effects of several nucleoside analogs—some of which are epigenetic reprogramming intermediates—in the U87 glioblastoma cell line. We found that two analogs, 5-hydroxymethyl-2′-deoxyuridine (5HmdU) and trifluorothymidine (TFT), are both cytotoxic and are efficiently incorporated into genomic DNA. In contrast, the 5-carboxy analogs—5-carboxy-2′-deoxyuridine (5CadU) and 5-carboxycytidine (5CadC)—showed no cytotoxicity and were not incorporated into DNA. Interestingly, 5-hydroxymethyl-2′-deoxycytidine (5HmdC) was cytotoxic but was not directly incorporated into DNA. Instead, it was deaminated into 5HmdU, which was then incorporated and likely responsible for the observed toxicity. 5HmdU is actively removed from DNA through the BER pathways. In contrast, TFT remains stably incorporated and is neither excised by BER nor does it hydrolyze into 5CadU—a known substrate for the DNA glycosylase SMUG1. We also found that N⁶-benzyladenosine (BzAdo), an inhibitor of the enzyme 2′-deoxynucleoside 5′-phosphate N-hydrolase (DNPH1), enhances the cytotoxicity of 5HmdU. However, the thymidine phosphorylase inhibitor tipiracil hydrochloride (TPI) does not increase the cytotoxic effect of TFT in U87 cells. Together, these findings highlight 5HmdU and TFT as promising chemotherapeutic agents for glioblastoma, each with distinct mechanisms of action and cellular processing. Full article

Objective: To characterize the profiles of resistance mutations to HIV reverse transcriptase inhibitors in Gabon. Design: Cross-sectional study conducted over 37 months, from October 2019 to October 2022, at the IST/HIV/AIDS Reference Laboratory, a reference center for the biological monitoring of people living with the human immunodeficiency virus (PWHIV) in Gabon. Methods: Plasma from 666 PWHIV receiving antiretroviral treatment was collected, followed by RNA extraction, amplification, and reverse transcriptase gene sequencing. Statistical analyses were performed using Stata^® 14.0 software (USA). Results: Six hundred and sixty-six (666) PWHIV plasma collected from 252 male and 414 female patients were analyzed and 1654 mutations were detected in 388 patients, including 849 (51.3%) associated with nucleoside reverse transcriptase inhibitors (NRTIs) and 805 (48.7%) with non-nucleoside reverse transcriptase inhibitors (NNRTIs). Three of the most prescribed treatment regimens were associated to the appearance of both NRTIs and NNRTIs resistance mutations: TDF + 3TC + EFV (24.02%; 160/666); TDF + FTC + EFV) (17.2%; 114/666) and AZT + 3TC + EFV (14.6%; 97/666). Additionally, stage 3 of CD4 T-lymphocyte deficiency, the higher viral load, and treatment duration are risk factors influencing the appearance of virus mutations. Also, treatment containing TDF-3TC + DTG is more protective against mutations. Conclusions: Drug resistance mutations are common in Gabon and compromise the efficacy of ART. Further study must search for other causes of therapeutic failure in Gabon in PWHIV. Full article

Human Immunodeficiency Virus (HIV) infection remains a major global health issue, with effective antiretroviral therapy (ART) extending life expectancy but also increasing age-related issues like osteopenia and osteoporosis. This cross-sectional study examines bone mineral density (BMD) and related risk factors in Romanian HIV-positive patients, emphasizing regional and therapy influences. The patients varying in HIV infection duration underwent DXA scanning to measure BMD in the lumbar spine, femoral neck, and total femur. A high prevalence of low BMD, especially in the lumbar spine, was identified along with significant associations between reduced BMD and factors such as smoking, alcohol use, vitamin D deficiency and serum phosphorus levels. ART like Protease Inhibitors and Nucleoside Reverse Transcriptase Inhibitors were linked to increased bone loss, emphasizing the multifactorial nature of osteoporosis in HIV-infected individuals and underscore the importance of regular BMD assessments, lifestyle adjustments, and careful management of antiretroviral therapy to minimize fracture risk and enhance overall health and quality of life. Full article

Pregnancy introduces significant physiological changes that alter the pharmacokinetics (PK) of antiretroviral therapy (ART), impacting its safety and efficacy in HIV-positive women. Optimizing ART during pregnancy is critical to maintaining maternal virological suppression and preventing mother-to-child transmission (MTCT) of HIV. This review evaluates the impact of pregnancy-induced PK changes on ART and proposes strategies for tailored regimens to improve outcomes. A comprehensive review of published literature was conducted, focusing on PK adaptations during pregnancy and their implications for different ART classes, including protease inhibitors (PIs), integrase strand transfer inhibitors (INSTIs), and nucleoside reverse transcriptase inhibitors (NRTIs). Key studies were analyzed to assess drug exposure, efficacy, and safety. Pregnancy significantly alters the PK of antiretrovirals, with increased hepatic metabolism, renal clearance, and changes in plasma protein binding leading to reduced drug exposure. For example, drugs like lopinavir and atazanavir require dose adjustments, while dolutegravir maintains efficacy despite reduced plasma levels. Integrase inhibitors demonstrate favorable virological suppression, although cobicistat-boosted regimens show subtherapeutic levels. Tailored approaches, such as therapeutic drug monitoring (TDM), optimize ART efficacy while minimizing toxicity. Pregnancy-specific PK changes necessitate evidence-based ART adjustments to ensure virological suppression and reduce MTCT risk. Incorporating TDM, leveraging pharmacogenomic insights, and prioritizing maternal and neonatal safety are critical for personalized ART management. Further research into long-acting formulations and global guideline harmonization is needed to address disparities in care and improve outcomes for HIV-positive pregnant women. Full article

The repurposing potential of Efavirenz (EFV), a clinically established non-nucleoside reverse transcriptase inhibitor, was comprehensively evaluated for its in vitro antibacterial effect either alone or in combination with other antibacterial agents on several Gram-positive clinical strains showing different antibiotic resistance profiles. The binding potential assessed by an in silico study included Penicillin-binding proteins (PBPs) and WalK membrane kinase. Despite the relatively high minimum inhibitory concentration (MIC) limiting the use of EFV as a single antibacterial agent, it exhibits significant synergistic activity at sub-MIC levels when paired with various antibiotics against Enterococcus species and Staphylococcus aureus. EFV showed restored sensitivity of β-lactams against Methicillin-resistant S. aureus (MRSA). It increased the effectiveness of antibiotics tested against Methicillin-sensitive S. aureus (MSSA). It also helped to overcome the intrinsic resistance barrier for several antibiotics in Enterococcus spp. In silico binding studies aligned remarkably with experimental antimicrobial testing results and highlighted the potential of EFV to direct the engagement of PBPs with moderate to strong binding affinities (pK_a 5.2–6.1). The dual-site PBP2 binding mechanism emerged as a novel inhibition strategy, potentially circumventing resistance mutations. Special attention should be paid to WalK binding predictions (pK_a = 4.94), referring to the potential of EFV to interfere with essential regulatory pathways controlling cell wall metabolism and virulence factor expression. These findings, in general, suggest the possibility of EFV as a promising lead for the development of new antibacterial agents. Full article

(1) Background: The highly pathogenic avian influenza virus H5N1 clade 2.3.4.4b is an emerging threat that poses a great risk to the poultry industry. A few human cases have been linked to the infection with this clade in many parts of the world, including the USA. Unfortunately, there are no specific vaccines or antiviral drugs that could help prevent and treat the infection caused by this virus in birds. Our major objective is to identify/repurpose some (novel/known) antiviral compounds that may inhibit viral replication by targeting some key viral proteins. (2) Methods: We used state-of-the-art machine learning tools such as molecular docking and MD-simulation methods from Biovia Discovery Studio (v24.1.0.321712). The key target proteins such as hemagglutinin (HA), neuraminidase (NA), Matrix-2 protein (M2), and the cap-binding domain of PB2 (PB2/CBD) homology models were validated through structural assessment via DOPE scores, Ramachandran plots, and Verify-3D metrics, ensuring reliable structural representations, confirming their reliability for subsequent in silico approaches. These approaches include molecular docking followed by molecular dynamics simulation for 50 nanoseconds (ns), highlighting the structural stability and compactness of the docked complexes. (3) Results: Molecular docking revealed strong binding affinities for both sofosbuvir and GS441524, particularly with the NA and PB2/CBD protein targets. Among them, GS441524 exhibited superior interaction scores and a greater number of hydrogen bonds with key functional residues of NA and PB2/CBD. The MM-GBSA binding free energy calculations further supported these findings, as GS441524 displayed more favorable binding energies compared to several known standard inhibitors, including F0045S for HA, Zanamivir for NA, Rimantadine and Amantadine for M2, and PB2-39 for PB2/CBD. Additionally, 50 ns molecular dynamics simulations highlighted the structural stability and compactness of the GS441524-PB2/CBD complex, further supporting its potential as a promising antiviral candidate. Furthermore, hydrogen bond monitor analysis over the 50 ns simulation confirmed persistent and specific interactions between the ligand and proteins, suggesting that GS441524 may effectively inhibit the NA, and PB2/CBD might potentially disrupt PB2-mediated RNA synthesis. (4) Conclusions: Our findings are consistent with previous evidence supporting the antiviral activity of certain nucleoside analog inhibitors, including GS441524, against various coronaviruses. These results further support the potential repurposing of GS441524 as a promising therapeutic candidate against H5N1 avian influenza clade 2.3.4.4b. However, further functional studies are required to validate these in silico predictions and support the inhibitory action of GS441524 against the targeted proteins of H5N1, specifically clade 2.3.4.4b. Full article

Nucleobase and nucleoside analogs are critical components of antimetabolite chemotherapy treatments used to disrupt DNA replication and induce apoptosis in rapidly proliferating cancer cells. However, the development of resistance to these agents remains a major clinical challenge. This review explores the epigenetic mechanisms that contribute to acquired chemoresistance, focusing on DNA methylation, histone modifications, and non-coding RNAs (ncRNAs). These epigenetic alterations regulate key processes such as DNA repair, drug metabolism, cell transport, and autophagy, enabling cancer cells to survive and resist therapeutic pressure. We highlight how dysregulation of DNA methyltransferases (DNMTs) and histone acetyltransferases (HATs) modulates expression of transporters (e.g., hENT1, ABCB1), DNA repair enzymes (e.g., Polβ, BRCA1/2), and autophagy-related genes (e.g., CSNK2A1, BNIP3). Furthermore, emerging roles for long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) in regulating nucleoside export and DNA damage response pathways underscore their relevance as therapeutic targets. The interplay of these epigenetic modifications drives resistance to agents such as gemcitabine and 5-fluorouracil across multiple tumor types. We also discuss recent progress in therapeutic interventions, including DNMT and HDAC inhibitors, RNA-based therapeutics, and CRISPR-based epigenome editing. Full article

Rilpivirine (RPV, R278474) was highlighted in 2005, two years after the death of Dr. Paul Janssen, as the ideal non-nucleoside reverse transcriptase inhibitor (NNRTI) to treat HIV infections. For this purpose, it was subsequently combined with tenofovir disoproxil fumarate (TDF), tenofovir alafenamide (TAF), darunavir (boosted with ritonavir or cobicistat) or dolutegravir. Its wide-spread use is thanks to its combination with cabotegravir (CAB) in the form of a long-acting intramuscular injection once per month (QM), later twice per month (Q2M), for the treatment of adults, later extended to adolescents and pregnant women, with HIV infections. The long-acting CAB plus RPV should not be administered in patients treated with rifampicin or rifabutin, patients with virological failure or patients with resistance to CAB or RPV, or patients with hepatitis B virus (HBV) infection. Long-acting CAB+RPV may lead to pain at the site of injection which would diminish over time. Full article

Background: Myelotoxicity, usually manifested by moderate leukopenia (particularly neutropenia), is a well-known adverse drug reaction to azathioprine (AZA) therapy. Thiopurine methyltransferase (TMPT) and nucleoside diphosphate-linked moiety X-type motif 15 (NUDT15) genotyping are not routinely performed in patients starting AZA therapy due to their low cost-effectiveness. Additionally, the concomitant use of xanthine oxidase inhibitors and 5-aminosalicylates may slow the metabolism of 6-mercaptopurine. Case Description: We describe a case of a 26-year-old Caucasian man with Crohn’s disease and psoriatic arthritis treated with mesalazine and AZA (100 mg daily) who developed prolonged bone marrow aplasia and neutropenic fever after increasing the daily dose of AZA from 100 to 150 mg (from 44 to 66 mg/m²), without frequent total blood count monitoring. Discontinuation of AZA, multiple transfusions of red blood cells and platelet concentrate, filgrastim, empirical antibiotic therapy, and antiviral and antifungal prophylaxis were obtained after 11 days complete recovery of bone marrow aplasia. Methods: Genomic DNA genotyping of coding regions of TPMT (exons 2–9) and NUDT15 (exons 1–3). Results: Heterozygous alleles in the untranslated region (c.460G>A and c.719A>G) associated with TPMT deficiency and a benign variant (c.*7G>A) in the 3′-UTR of NUDT15 with no effect on enzyme activity were found. Conclusions: This case highlights the importance of monitoring the total blood count frequently during the first weeks of treatment with moderate-to-high doses of AZA. Furthermore, the interaction between AZA and mesalazine may play a significant role in the development of prolonged bone marrow aplasia. Full article

The synthesis of a new acyclic and cyclic series of D-Ala-AMP analogues was reported. Chemical modifications were introduced on the carbohydrate, the sulfamate linker, and/or the amino-acid N-terminal moiety in order to increase in vivo stability and cell permeability. These new compounds were evaluated in vitro as DltA inhibitors and also in vivo as adjuvant antibiotics to re-sensitize methicillin-resistant Staphylococcus aureus. Indeed, we showed that seven nucleosides containing either a fluorine atom, an azido group, a difluorophosphonylated allylic ether moiety onto the 2′-position, or a sulfamate and a triazole as the sulfamate linker had moderate to excellent IC₅₀ values. Among all these new DltA inhibitors, two molecules functionalized by the fluorinated ether or the sulfamide linker were able to efficiently re-sensitize MRSA to imipenem. Quantification of D-alanyl esters confirmed that these two compounds reduced the level of bacterial cell wall D-alanyl residues by 50% and 80%. Full article

In this study, we investigated the proportion of transmitted drug resistance (TDR) mutations and human immunodeficiency virus (HIV)-1 subtypes among 487 antiretroviral therapy (ART)-naïve individuals in South Korea from 2021 to 2024 to inform more effective treatment strategies. Consistent with previous reports, subtype B was most prevalent among HIV-1 subtypes at 50.7%; however, its proportion decreased annually (p = 0.047). Various subtypes of circulating recombinant forms (CRFs) were analyzed in this study, resulting in high genetic diversity. The subtype distributions of Korean and non-Korean patients differed, with subtype B (53.7%) and CRF01_AE (34.4%) being dominant in the former and latter, respectively. TDR across antiretroviral drug classes was approximately 3.5% in South Korea. Non-nucleoside reverse transcriptase inhibitors elicited the greatest drug resistance, which increased from 2021 to 2023, with a slight decrease in 2024. The integrase strand transfer inhibitor drugs, elvitegravir and raltegravir, most frequently exhibited high resistance scores. We provide a comprehensive overview of the HIV-1 genetic distribution and TDR patterns in South Korea from 2021 to 2024. Within the broader context of HIV-1 epidemiology in Asia and the Pacific, the findings contribute to a comprehensive understanding of the global distribution of HIV-1 resistance and genotypes, enabling the development of effective interventions. Full article

Alzheimer’s disease (AD) is considered one of the main pathologies of our time, whose incidence and prevalence are suggested to be strongly underestimated. AD presents as a complex neurodegenerative condition characterized by marked neuroinflammation and a significant decline in the cognitive and mnemonic functions of affected patients. Recognized AD pathological hallmarks include amyloid beta plaque and neurofibrillary tangle formation, synaptic dysfunction with considerable apoptosis of cholinergic and dopaminergic neurons, and high levels of oxidative stress and neuroinflammation. The available pharmacological treatments are represented by acetylcholinesterase inhibitors to treat the mild to moderate form of the disease and N-methyl-D-aspartate inhibitors alone or in combination with the previously cited ones in the late stage of the neurodegenerative condition. Furthermore, emerging drug therapies such as monoclonal antibodies are promising agents in AD management. Although scientific evidence highlights these chemicals as effective in slowing down disease progression, significant limitations behind their employment derive from the notable dose-dependent side effects and the single-target mechanism of action. In this context, two well-studied phytotherapeutics, W. somnifera (W. somnifera) and fungi belonging to the genus Cordyceps, have gained attention for their chemical composition regarding their neuroprotective and anti-inflammatory effects. Ashwagandha (obtained principally from the roots of W. somnifera) is an adaptogen that relieves stress and anxiety. It contains several ergostane-type steroidal lactones—such as withanolides and withaferin A—and various alkaloids, contributing to its antioxidant and neuroprotective effects. Likewise, cordycepin is the main bioactive principle found in Cordyceps fungi. This natural nucleoside has been reported to possess therapeutic potential as an anti-cancer, immunomodulatory, and anti-inflammatory agent, with some studies suggesting a beneficial role in AD treatment. The purpose of the present review is to investigate the pharmacological properties of W. somnifera and Cordyceps species in the context of AD treatment and explore the therapeutic potential of the constitutive bioactive molecules in preclinical models mimicking this neurodegenerative condition. Full article

The replication machinery of SARS-CoV-2 is a primary target for therapeutic intervention, and has led to significant progress in antiviral medication discovery. This review consolidates contemporary molecular insights into viral replication and rigorously assesses treatment methods at different phases of viruses’ clinical development. Direct-acting antivirals, such as nucleoside analogs (e.g., remdesivir, molnupiravir) and protease inhibitors (e.g., nirmatrelvir), have shown clinical effectiveness in diminishing morbidity and hospitalization rates. Simultaneously, host-targeted medicines like baricitinib, camostat, and brequinar leverage critical host–virus interactions, providing additional pathways to reduce viral replication while possibly minimizing the development of resistance. Notwithstanding these advancements, constraints in distribution methods, antiviral longevity, and the risk of mutational evasion demand novel strategies. Promising investigational approaches encompass CRISPR-mediated RNA degradation systems, inhalable siRNA-nanoparticle conjugates, and molecular glue degraders that target host and viral proteins. Furthermore, next-generation treatments aimed at underutilized enzyme domains (e.g., NiRAN, ExoN) and host chaperone systems (e.g., TRiC complex) signify a transformative approach in antiviral targeting. The integration of high-throughput phenotypic screening, AI-driven medication repurposing, and systems virology is transforming the antiviral discovery field. An ongoing interdisciplinary endeavor is necessary to convert these findings into versatile, resistance-resistant antiviral strategies that are applicable beyond the present pandemic and in future coronavirus epidemics. Full article

Background: Argentina has reported moderate to high levels of transmitted drug resistance in people living with HIV/AIDS (PLWHA), mostly to non-nucleoside reverse transcriptase inhibitors (NNRTIs). Doravirine (DOR) has a unique resistance profile and retains potent antiviral activity in the presence of the most prevalent NNRTI-associated resistant viruses. Scarce data exist regarding the frequency of DOR resistance-associated mutations (RAMs) in Latin America. We describe the prevalence of DOR RAMs in samples from adults PLWHA in Buenos Aires, Argentina, in the context of a survey of transmitted drug resistance (TDR). Material and Methods: A cross-sectional study was undertaken utilizing samples collected between 2017 and 2021 at two reference HIV clinics. Samples were analyzed for RAMs using the World Health Organization (WHO) mutation list. Mutations to DOR were assessed with the Stanford and Agence Nationale de Recherches sur le SIDA (ANRS) algorithms. Rilpivirine (RPV) RAMs were assessed using the Stanford algorithm. Susceptibility to NNRTIs was evaluated using the HIVdb Program with Stanford and ANRS criteria. Results: Samples from 1667 PLWHA were analyzed: 81.2% were male, with 52.6% identifying as men who have sex with men. According to the WHO list, the overall TDR was 12.1% (n = 203). The prevalence of RAMs was 10.1% (170/1667) for NNRTIs, 4% (67/1667) for nucleoside reverse-transcriptase inhibitors (NRTIs), and 1.7% (30/1667) for protease inhibitors (PIs). The most frequent NNRTI mutations were K103N (5.6%), G190A (0.89%), and K103S (0.77%). The prevalence of DOR RAMs was <2%, with the most common being Y188L (0.53%). Rilpivirine RAM prevalence was 6%. Susceptibility to DOR, RPV, efavirenz, and nevirapine as given by the Stanford algorithm was 97.4%, 92%, 91.4%, and 90.4%, respectively. The ANRS criteria yielded susceptibility rates of 98.3%, 93.3%, 92.3%, and 90.8%, respectively. Regarding NRTIs, thymidine analog mutations (including T215 revertants) were the most frequent RAMs. Among PIs, the most prevalent RAMs were M46L (0.47%) and V82A (0.35%). Conclusions: Our study shows the persistence of moderate to high levels of resistance to first-generation NNRTIs. Despite this, prevalence was low for DOR. Surveillance of TDR remains critical for recommendations of ART initiation. Full article