Microliquid/Liquid Interfacial Sensors: Biomimetic Investigation of Transmembrane Mechanisms and Real-Time Determinations of Clemastine, Cyproheptadine, Epinastine, Cetirizine, and Desloratadine.

Antihistamines relieve allergic symptoms by inhibiting the action of histamine. Further understanding of antihistamine transmembrane mechanisms and optimizing the selectivity and real-time monitoring capabilities of drug sensors is necessary. In this study, a micrometer liquid/liquid (L/L) interfacial sensor has served as a biomimetic membrane to investigate the mechanism of interfacial transfer of five antihistamines, i.e., clemastine (CLE), cyproheptadine (CYP), epinastine (EPI), desloratadine (DSL), and cetirizine (CET), and realize the real-time determinations. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques have been used to uncover the electrochemical transfer behavior of the five antihistamines at the L/L interface. Additionally, finite element simulations (FEMs) have been employed to reveal the thermodynamics and kinetics of the process. Visualization of antihistamine partitioning in two phases at different pH values can be realized by ion partition diagrams (IPDs). The IPDs also reveal the transfer mechanism at the L/L interface and provide effective lipophilicity at different pH values. Real-time determinations of these antihistamines have been achieved through potentiostatic chronoamperometry (I-t), exhibiting good selectivity with the addition of nine common organic or inorganic compounds in living organisms and revealing the potential for in vivo pharmacokinetics. Besides providing a satisfactory surrogate for studying the transmembrane mechanism of antihistamines, this work also sheds light on micro- and nano L/L interfacial sensors for in vivo analysis of pharmacokinetics at a single-cell or single-organelle level.

Discovery of the novel and potent histamine H1 receptor antagonists for treatment of allergic diseases.

Desloratadine, a second-generation histamine H1 receptor antagonist, has established itself as a first-line drug for the treatment of allergic diseases. Despite its effectiveness, desloratadine exhibits an antagonistic effect on muscarinic M3 receptor, which can cause side effects such as dry mouth and urinary retention, ultimately limiting its clinical application. Herein, we describe the discovery of compound Ⅲ-4, a novel H1 receptor antagonist with significant H1 receptor antagonistic activity (IC50 = 24.12 nM) and enhanced selectivity towards peripheral H1 receptor. In particular, Ⅲ-4 exhibits reduced M3 receptor inhibitory potency (IC50 > 10,000 nM) and acceptable hERG inhibitory activity (17.6 ± 2.1 µM) compare with desloratadine. Additionally, Ⅲ-4 exhibits favorable pharmacokinetic properties, as well as in vivo efficacy and safety profiles. All of these reveal that Ⅲ-4 has potential to emerge as a novel H1 receptor antagonist for the treatment of allergic diseases. More importantly, the compound Ⅲ-4 (HY-078020) has recently been granted clinical approval.

Desloratadine alleviates ALS-like pathology in hSOD1G93A mice via targeting 5HTR2A on activated spinal astrocytes.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with progressive loss of motor neurons in the spinal cord, cerebral cortex and brain stem. ALS is characterized by gradual muscle atrophy and dyskinesia. The limited knowledge on the pathology of ALS has impeded the development of therapeutics for the disease. Previous studies have shown that autophagy and astrocyte-mediated neuroinflammation are involved in the pathogenesis of ALS, while 5HTR2A participates in the early stage of astrocyte activation, and 5HTR2A antagonism may suppress astrocyte activation. In this study, we evaluated the therapeutic effects of desloratadine (DLT), a selective 5HTR2A antagonist, in human SOD1G93A (hSOD1G93A) ALS model mice, and elucidated the underlying mechanisms. HSOD1G93A mice were administered DLT (20 mg·kg-1·d-1, i.g.) from the age of 8 weeks for 10 weeks or until death. ALS onset time and lifespan were determined using rotarod and righting reflex tests, respectively. We found that astrocyte activation accompanying with serotonin receptor 2 A (5HTR2A) upregulation in the spinal cord was tightly associated with ALS-like pathology, which was effectively attenuated by DLT administration. We showed that DLT administration significantly delayed ALS symptom onset time, prolonged lifespan and ameliorated movement disorders, gastrocnemius injury and spinal motor neuronal loss in hSOD1G93A mice. Spinal cord-specific knockdown of 5HTR2A by intrathecal injection of adeno-associated virus9 (AAV9)-si-5Htr2a also ameliorated ALS pathology in hSOD1G93A mice, and occluded the therapeutic effects of DLT administration. Furthermore, we demonstrated that DLT administration promoted autophagy to reduce mutant hSOD1 levels through 5HTR2A/cAMP/AMPK pathway, suppressed oxidative stress through 5HTR2A/cAMP/AMPK/Nrf2-HO-1/NQO-1 pathway, and inhibited astrocyte neuroinflammation through 5HTR2A/cAMP/AMPK/NF-κB/NLRP3 pathway in the spinal cord of hSOD1G93A mice. In summary, 5HTR2A antagonism shows promise as a therapeutic strategy for ALS, highlighting the potential of DLT in the treatment of the disease. DLT as a 5HTR2A antagonist effectively promoted autophagy to reduce mutant hSOD1 level through 5HTR2A/cAMP/AMPK pathway, suppressed oxidative stress through 5HTR2A/cAMP/AMPK/Nrf2-HO-1/NQO-1 pathway, and inhibited astrocytic neuroinflammation through 5HTR2A/cAMP/AMPK/NF-κB/NLRP3 pathway in the spinal cord of hSOD1G93A mice.

Loratidine is associated with improved prognosis and exerts antineoplastic effects via apoptotic and pyroptotic crosstalk in lung cancer.

BACKGROUND: Tumor-associated inflammation suggests that anti-inflammatory medication could be beneficial in cancer therapy. Loratadine, an antihistamine, has demonstrated improved survival in certain cancers. However, the anticancer mechanisms of loratadine in lung cancer remain unclear. OBJECTIVE: This study investigates the anticancer mechanisms of loratadine in lung cancer. METHODS: A retrospective cohort of 4,522 lung cancer patients from 2006 to 2018 was analyzed to identify noncancer drug exposures associated with prognosis. Cellular experiments, animal models, and RNA-seq data analysis were employed to validate the findings and explore the antitumor effects of loratadine. RESULTS: This retrospective study revealed a positive association between loratadine administration and ameliorated survival outcomes in lung cancer patients, exhibiting dose dependency. Rigorous in vitro and in vivo assays demonstrated that apoptosis induction and epithelial-mesenchymal transition (EMT) reduction were stimulated by moderate loratadine concentrations, whereas pyroptosis was triggered by elevated dosages. Intriguingly, loratadine was found to augment PPARγ levels, which acted as a gasdermin D transcription promoter and caspase-8 activation enhancer. Consequently, loratadine might incite a sophisticated interplay between apoptosis and pyroptosis, facilitated by the pivotal role of caspase-8. CONCLUSION: Loratadine use is linked to enhanced survival in lung cancer patients, potentially due to its role in modulating the interplay between apoptosis and pyroptosis via caspase-8.

Loratadine Combats Methicillin-Resistant Staphylococcus aureus by Modulating Virulence, Antibiotic Resistance, and Biofilm Genes.

Methicillin-resistant Staphylococcus aureus (MRSA) has evolved to become resistant to multiple classes of antibiotics. New antibiotics are costly to develop and deploy, and they have a limited effective lifespan. Antibiotic adjuvants are molecules that potentiate existing antibiotics through nontoxic mechanisms. We previously reported that loratadine, the active ingredient in Claritin, potentiates multiple cell-wall active antibiotics in vitro and disrupts biofilm formation through a hypothesized inhibition of the master regulatory kinase Stk1. Loratadine and oxacillin combined repressed the expression of key antibiotic resistance genes in the bla and mec operons. We hypothesized that additional genes involved in antibiotic resistance, biofilm formation, and other cellular pathways would be modulated when looking transcriptome-wide. To test this, we used RNA-seq to quantify transcript levels and found significant effects in gene expression, including genes controlling virulence, antibiotic resistance, metabolism, transcription (core RNA polymerase subunits and sigma factors), and translation (a plethora of genes encoding ribosomal proteins and elongation factor Tu). We further demonstrated the impacts of these transcriptional effects by investigating loratadine treatment on intracellular ATP levels, persister formation, and biofilm formation and morphology. Loratadine minimized biofilm formation in vitro and enhanced the survival of infected Caenorhabditis elegans. These pleiotropic effects and their demonstrated outcomes on MRSA virulence and survival phenotypes position loratadine as an attractive anti-infective against MRSA.

The Combination Sorafenib-raloxifene-loratadine as a Novel Potential Therapeutic Approach Against Human Liver Cancer.

BACKGROUND/AIM: Liver cancer is one of the malignancies with the highest mortality-to-incidence ratio worldwide. Therefore, novel therapeutic approaches are urgently needed. Combination therapy and drug repurposing can improve the response of the patients to therapy in several cancers. The aim of the present study was to merge these two strategies and evaluate whether the two-drug- or three-drug- combination of sorafenib, raloxifene, and loratadine improves the antineoplastic effect on human liver cancer cells in comparison to the single-drug effect. MATERIALS AND METHODS: The human liver cancer cell lines HepG2 and HuH7 were studied. The effect of sorafenib, raloxifene, and loratadine on the metabolic activity was determined using the MTT assay. The inhibitory concentrations (IC20 and IC50) were calculated from these results and used in the drug-combination experiments. Apoptosis and cell survival were studied by flow cytometry and using the colony formation assay, respectively. RESULTS: In both cell lines, sorafenib, raloxifene, and loratadine in two-drug and three-drug combinations significantly reduced metabolic activity and significantly increased the percentage of apoptotic cells compared to the single-drug effect. In addition, all the combinations significantly reduced the colony-forming capacity in the HepG2 cell line. Surprisingly, the effect of raloxifene on apoptosis was similar to that observed using the combinations. CONCLUSION: The triple combination sorafenib-raloxifene-loratadine may be a novel promising approach in the treatment of liver cancer patients.

Re-evaluation of over-the-counter histamine H1-receptor antagonists based on their effects on murine models of allergen-induced nasal hyperresponsiveness.

T cells play an essential role in the development of allergen-induced nasal hyperresponsiveness (NHR), a pathophysiological response in allergic rhinitis. The effects of histamine H1-receptor antagonists (antihistamines) on murine NHR models were investigated. Intragastric epinastine, fexofenadine, and loratadine administration suppressed allergen-induced immediate nasal response but not NHR in immunized mice. Regardless of the alleviation of stimulation-induced Th2 cytokine expression by loratadine and desloratadine in vitro, allergen-induced NHR and nasal eosinophil infiltration in Th2 cell-transferred mice were unaffected by loratadine in vivo. This influence on T cell-mediated NHR was excluded from the pharmacological effects of antihistamines.

Loratadine, an antihistaminic drug, suppresses the proliferation of endometrial stromal cells by inhibition of TRPV2.

The transient receptor potential (TRP) channel TRPV2 is widely expressed in a variety of different cell types and tissues. However, elucidating the exact biological functions of TRPV2 is significantly hampered by the lack of selective pharmacological tools to modulate channel activity in vitro and in vivo. This study aimed to identify new compounds that modify TRPV2 activity via the use of a plate-based calcium imaging approach to screen a drug repurposing library. Three antihistaminic drugs, loratadine, astemizole and clemizole were identified to reduce calcium-influx evoked by the TRPV2 agonist tetrahydrocannabivarin in HEK293 cells expressing murine TRPV2. Using single-cell calcium-microfluorimetry and whole-cell patch clamp recordings, we further confirmed that all three compounds induced a concentration-dependent block of TRPV2-mediated Ca2+ influx and whole-cell currents, with loratadine being the most potent antagonist of TRPV2. Moreover, this study demonstrated that loratadine was able to block both the human and mouse TRPV2 orthologs, without inhibiting the activity of other closely related members of the TRPV superfamily. Finally, loratadine inhibited TRPV2-dependent responses in a primary culture of mouse endometrial stromal cells and attenuated cell proliferation and migration in in vitro cell proliferation and wound healing assays. Taken together, our study revealed that the antihistaminic drugs loratadine, astemizole and clemizole target TRPV2 in a concentration-dependent manner. The identification of these antihistaminic drugs as blockers of TRPV2 may form a new starting point for the synthesis of more potent and selective TRPV2 antagonists, which could further lead to the unravelling of the physiological role of the channel.

Loratadine.

Loratadine, 4-(8-Chloro-5,6-dihydro-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ylidene)-1-piperidinecarboxylic acid ethyl ester, is an antihistamine drug with long-acting effects and has limited selectivity for peripheral H1 receptors. It is widely used for the prevention of allergic diseases such as rhinitis chronic urticaria, and asthma. This chapter discusses, by a critical extensive review of the literature, the description of loratadine in terms of its names, formulae, elemental composition, appearance, methods of preparation. The profile contains physicochemical properties of Loratadine, including pKa value, solubility and X-ray powder diffraction. In addition, it involves Fourier transform infrared spectrometry, nuclear magnetic resonance spectroscopy and mass spectroscopy for functional groups and structural confirmation of. The chapter also includes methods of analysis of the drug such as compendial, titrimetric, electrochemical, spectroscopic, chromatographic and capillary electrophoretic methods. The chapter also covers clinical applications of the drug such as its uses, doses, ADME profiles and mechanism of action.

Anti-Inflammatory Activities of an Anti-Histamine Drug, Loratadine, by Suppressing TAK1 in AP-1 Pathway.

Loratadine is an anti-histamine routinely used for treating allergies. However, recent findings have shown that Loratadine may also have anti-inflammatory functions, while their exact mechanisms have not yet been fully uncovered. In this paper, we investigated whether Loratadine can be utilized as an anti-inflammatory drug through a series of in vitro and in vivo experiments using a murine macrophage cell line and an acute gastritis mouse model. Loratadine was found to dramatically reduce the expression of pro-inflammatory genes, including MMP1, MMP3, and MMP9, and inhibit AP-1 transcriptional activation, as demonstrated by the luciferase assay. Therefore, we decided to further explore its role in the AP-1 signaling pathway. The expression of c-Jun and c-Fos, AP-1 subunits, was repressed by Loratadine and, correspondingly, the expression of p-JNK, p-MKK7, and p-TAK1 was also inhibited. In addition, Loratadine was able to reduce gastric bleeding in acute gastritis-induced mice; Western blotting using the stomach samples showed reduced p-c-Fos protein levels. Loratadine was shown to effectively suppress inflammation by specifically targeting TAK1 and suppressing consequent AP-1 signaling pathway activation and inflammatory cytokine production.

Increasing Angiogenesis Factors in Hypoxic Diabetic Wound Conditions by siRNA Delivery: Additive Effect of LbL-Gold Nanocarriers and Desloratadine-Induced Lysosomal Escape.

Impaired wound healing in people with diabetes has multifactorial causes, with insufficient neovascularization being one of the most important. Hypoxia-inducible factor-1 (HIF-1) plays a central role in the hypoxia-induced response by activating angiogenesis factors. As its activity is under precise regulatory control of prolyl-hydroxylase domain 2 (PHD-2), downregulation of PHD-2 by small interfering RNA (siRNA) could stabilize HIF-1α and, therefore, upregulate the expression of pro-angiogenic factors as well. Intracellular delivery of siRNA can be achieved with nanocarriers that must fulfill several requirements, including high stability, low toxicity, and high transfection efficiency. Here, we designed and compared the performance of layer-by-layer self-assembled siRNA-loaded gold nanoparticles with two different outer layers-Chitosan (AuNP@CS) and Poly L-arginine (AuNP@PLA). Although both formulations have exactly the same core, we find that a PLA outer layer improves the endosomal escape of siRNA, and therefore, transfection efficiency, after endocytic uptake in NIH-3T3 cells. Furthermore, we found that endosomal escape of AuNP@PLA could be improved further when cells were additionally treated with desloratadine, thus outperforming commercial reagents such as Lipofectamine® and jetPRIME®. AuNP@PLA in combination with desloratadine was proven to induce PHD-2 silencing in fibroblasts, allowing upregulation of pro-angiogenic pathways. This finding in an in vitro context constitutes a first step towards improving diabetic wound healing with siRNA therapy.

Efficiency and safety of desloratadine in combination with compound glycyrrhizin in the treatment of chronic urticaria: a meta-analysis and systematic review of randomised controlled trials.

CONTEXT: Desloratadine, an H1 receptor antagonist, is suggested as an effective first-line drug for chronic urticarial (CU). However, the efficacy of desloratadine alone is limited, and the recurrence rate of CU is relatively high. OBJECTIVE: We sought to evaluate the efficacy and clinical feasibility of desloratadine in combination with compound glycyrrhizin in the treatment of CU. MATERIALS AND METHODS: A systematic literature search was conducted in the databases of the China National Knowledge Infrastructure Database, VIP, WanFang, PubMed, and Web of Science using subject terms: "Chronic urticaria", "Loratadine", and "Compound glycyrrhizin". Randomised controlled trials (RCTs) that compared the efficiency and safety of the combination treatment with desloratadine alone starting from January 1, 2014 until February 10, 2021 were selected by two co-first authors independently, and the extracted data were analysed using Rev Man 5.3 software. RESULTS: Fourteen RCTs were included in our meta-analysis with a total of 1501 patients. The results showed that the combination treatment yielded a better treatment effect (total response rate: RR = 1.23, 95% CI: 1.17 to 1.29, p < 0.00001; cure rate: RR = 1.50, 95% CI: 1.30 to 1.73, p < 0.00001), lower recurrence rate as well as superior immune improvement than the treatment with desloratadine alone. In addition, there was no significant difference in the safety of the two treatments. DISCUSSION AND CONCLUSION: The combination of desloratadine and compound glycyrrhizin is a promising treatment for CU and is associated with decreased serum IgE level and improved proportions of CD4+ T and CD8+ T cells.

Antihistamines Modulate Functional Activity of Macrophages.

We compared the effects of the first-, second- and third-generation antihistamines in different doses on enzyme activity and cytokine production by macrophages and their death using an in vitro model. It was found that decreasing the dose led to an increase in the number of viable cells; after contact with second-generation antihistamines (loratadine, desloratadine), apoptosis of macrophages predominated. A dose-dependent increase in activity of ATPase and 5'-AMP with less pronounced effect of second-generation drugs was revealed. It was shown that under the influence of drugs, macrophages do not produce IL-1ß, but actively synthesize TNFα and IL-10, which indicates the immunomodulatory properties of these drugs.

Testing of the inhibitory effects of loratadine and desloratadine on SARS-CoV-2 spike pseudotyped virus viropexis.

Currently, there is an urgent need to find a treatment for the highly infectious coronavirus disease (COVID-19). However, the development of a new, effective, and safe vaccine or drug often requires years and poses great risks. At this critical stage, there is an advantage in using existing clinically approved drugs to treat COVID-19. In this study, in vitro severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike pseudotyped viral infection experiments indicated that histamine H1 antagonists loratadine (LOR) and desloratadine (DES) could prevent entry of the pseudotyped virus into ACE2-overexpressing HEK293T cells and showed that DES was more effective. Further binding experiments using cell membrane chromatography and surface plasmon resonance demonstrated that both antagonists could bind to ACE2 and that the binding affinity of DES was much stronger than that of LOR. Molecular docking results elucidated that LOR and DES could bind to ACE2 on the interface of the SARS-CoV-2-binding area. Additionally, DES could form one hydrogen bond with LYS31 but LOR binding relied on non-hydrogen bonds. To our knowledge, this study is the first to demonstrate the inhibitory effect of LOR and DES on SARS-CoV-2 spike pseudotyped virus viropexis by blocking spike protein-ACE2 interaction. This study may provide a new strategy for finding an effective therapeutic option for COVID-19.

A novel nasal co-loaded loratadine and sulpiride nanoemulsion with improved downregulation of TNF-α, TGF-ß and IL-1 in rabbit models of ovalbumin-induced allergic rhinitis.

PURPOSE: The work aimed to develop a co-loaded loratadine and sulpiride nasal nanoemulsion for allergic rhinitis management. METHODS: Compatibility studies were conducted adopting differential scanning calorimetry and Fourier transform infrared spectroscopy. Nanoemulsion formulations were prepared using soybean lecithin, olive oil and tween 80. Sodium cholate and glycerol were employed as co-surfactants. Nanoemulsions were assessed for viscosity, pH, droplet size, polydispersity index, zeta potential, electrical conductivity, entrapment, In vitro drug release and corresponding kinetics. Stability of the selected formulation was investigated. The biological effectiveness was evaluated in rabbit models of ovalbumin-induced allergic rhinitis by measuring TNF-α, TGF-ß and IL-1. RESULTS: Compatibility studies revealed absence of drug/drug interactions. Nanoemulsions exhibited > 90% entrapment efficiency. The selected nanoemulsion demonstrated small droplet size (85.2 ± 0.2 nm), low PDI (0.35 ± 0.0) and appropriate Zeta Potential (-23.3 ± 0.2) and stability. It also displayed enhanced in vitro drug release following the Higuashi Diffusion and Baker-Lonsdale models. The mean relative mRNA expression of TNF-α, IL-1 and TGF-ß significantly decreased from 9.59 ± 1.06, 4.15 ± 0.02 and 4.15 ± 0.02 to 1.28 ± 0.02, 1.93 ± 0.06 and 1.56 ± 0.02 respectively after treatment with the selected nanoemulsion formulation. CONCLUSION: The results reflected a promising potent effect of the combined loratadine and sulpiride nasal nanoemulsion in managing the symptoms of allergic rhinitis.

Assessing the effect of prolonged use of desloratadine on adipose Brillouin shift and composition in rats.

Antihistamines, which are commonly used to treat allergic reactions, are known for their side effects, which contribute to weight gain. It is hypothesized that simultaneous Brillouin elastography and Raman spectroscopy can be used to detect changes in adipose tissue associated with a prolonged intake of desloratadine, a commonly used second generation antihistamine. White and brown adipose tissue samples were excised from adult rats following 16 weeks of daily administration of desloratadine. It was found that the prolonged intake of desloratadine leads to an increase in Brillouin shift in both adipose tissue types. Raman spectra indicate that antihistamine use reduces protein-to-lipid ratio in brown adipose tissue but not white adipose tissue, indicating the effect on adipose tissue is location-dependent.

Desloratadine inhibits heterotopic ossification by suppression of BMP2-Smad1/5/8 signaling.

Heterotopic ossification (HO) is a pathological condition in which ectopic bone forms within soft tissues such as skeletal muscle. Human platelet-derived growth factor receptor α positive (PDGFRα+) cells, which were proved to be the original cells of HO were incubated in osteogenic differentiation medium with Food and Drug Administration-approved compounds. Alkaline phosphatase activity was measured as a screening to inhibit osteogenic differentiation. For the compounds which inhibited osteogenic differentiation of PDGFRα+ cells, we examined dose dependency of its effect using alizarin red S staining and its cell toxicity using WST-8. In addition, regulation of bone morphogenetic proteins (BMP)-Smad signaling which is the major signal of osteogenic differentiation was investigated by Western blotting to elucidate the mechanism of osteogenesis inhibitory effect by the compound. In vivo experiment, complete transverse incision of Achilles tendons in mice was made and mice were fed the compound by mixing with drinking water after operation. Ten weeks after operation, we assessed and quantified HO by micro-computed tomography scan. Intriguingly, we discovered desloratadine inhibited osteogenic differentiation of PDGFRα+ cells using the drug repositioning method. Desloratadine inhibited osteogenic differentiation of the cells dose dependently without cell toxicity. Desloratadine suppressed phosphorylation of Smad1/5/8 induced by BMP2 in PDGFRα+ cells. In Achilles tenotomy mice model, desloratadine treatment significantly inhibited ectopic bone formation compared with control. In conclusion, we discovered desloratadine inhibited osteogenic differentiation using human PDGFRα+ cells and proved its efficacy using Achilles tenotomy ectopic bone formation model in vivo. Our study paved the way to inhibit HO in early clinical use because of its guaranteed safety.

Antiallergic drug desloratadine as a selective antagonist of 5HT2A receptor ameliorates pathology of Alzheimer's disease model mice by improving microglial dysfunction.

Alzheimer's disease (AD) is a progressively neurodegenerative disease characterized by cognitive deficits and alteration of personality and behavior. As yet, there is no efficient treatment for AD. 5HT2A receptor (5HT2A R) is a subtype of 5HT2 receptor belonging to the serotonin receptor family, and its antagonists have been clinically used as antipsychotics to relieve psychopathy. Here, we discovered that clinically first-line antiallergic drug desloratadine (DLT) functioned as a selective antagonist of 5HT2A R and efficiently ameliorated pathology of APP/PS1 mice. The underlying mechanism has been intensively investigated by assay against APP/PS1 mice with selective 5HT2A R knockdown in the brain treated by adeno-associated virus (AAV)-ePHP-si-5HT2A R. DLT reduced amyloid plaque deposition by promoting microglial Aß phagocytosis and degradation, and ameliorated innate immune response by polarizing microglia to an anti-inflammatory phenotype. It stimulated autophagy process and repressed neuroinflammation through 5HT2A R/cAMP/PKA/CREB/Sirt1 pathway, and activated glucocorticoid receptor (GR) nuclear translocation to upregulate the transcriptions of phagocytic receptors TLR2 and TLR4 in response to microglial phagocytosis stimulation. Together, our work has highly supported that 5HT2A R antagonism might be a promising therapeutic strategy for AD and highlighted the potential of DLT in the treatment of this disease.

Loratadine Alleviates Advanced Glycation End Product-Induced Activation of NLRP3 Inflammasome in Human Chondrocytes.

BACKGROUND: Chondrocytes in joint tissue are responsible for the synthesis and degradation of the cartilage matrix. Chondrocytes have been closely linked to the pathogenesis of osteoarthritis and cartilage damage. Targeted drug intervention directed at chondrocyte function is a promising strategy for the treatment of osteoarthritis. The effects of histamine receptor H1 (H1R) and its antagonist loratadine in osteoarthritic chondrocytes are less known. MATERIALS AND METHODS: The inhibitory effects of loratadine on NLRP3 inflammasome and the NADPH oxidase subunit NOX4 were assessed in advanced glycation end products (AGEs)-treated SW1353 chondrocytes by real-time PCR, ELISA, and Western blot experiments. The mitochondrial ROS level was measured using the specific probe MitoSOX Red. The dependent effect of loratadine on the transcriptional factor nuclear factor erythroid 2-related factor 2 (NRF2) was evaluated through an oligo-based siRNA knockdown approach and Western blot analysis. RESULTS: The expression of H1R was dose-responsively induced by AGEs in chondrocytes. Treatment with loratadine mitigated AGEs-induced oxidative stress, as revealed by suppressed production of mitochondrial ROS and the NADPH oxidase subunit NOX4. Loratadine treatment inhibited the expression of TxNIP and several components of the NLRP3 inflammasome complex, including NLRP3, ASC, and cleaved caspase 1 (P10). Moreover, loratadine suppressed the expression of NRF2, and the silencing of NRF2 abolished the suppressive effect of loratadine on NLRP3 inflammasome activation. CONCLUSION: Our study demonstrates that loratadine protects chondrocytes from AGEs-induced TxNIP/NLRP3 inflammasome activation by modulating the expression of the transcriptional factor NRF2. This finding implies that loratadine has therapeutic potential in the treatment of osteoarthritis and cartilage injury.

Asymmetric Catalysis upon Helically Chiral Loratadine Analogues Unveils Enantiomer-Dependent Antihistamine Activity.

Analogues of the conformationally dynamic Claritin (loratadine) and Clarinex (desloratadine) scaffolds have been enantio- and chemoselectively N-oxidized using an aspartic acid containing peptide catalyst to afford stable, helically chiral products in up to >99:1 er. The conformational dynamics and enantiomeric stability of the N-oxide products have been investigated experimentally and computationally with the aid of crystallographic data. Furthermore, biological assays show that rigidifying the core structure of loratadine and related analogues through N-oxidation affects antihistamine activity in an enantiomer-dependent fashion. Computational docking studies illustrate the observed activity differences.